Physics NEET MCQs

The core of a transformer is laminated to reduce energy losses due to  

Eddy currents

In the circuit given below, the reading of the voltmeter V will be:
            

  300 V

$\mathrm{An} \mathrm{alternating} \mathrm{current} \mathrm{is} \mathrm{given} \mathrm{as} \mathrm{i} = {\mathrm{i}}_1 \cos \mathrm{\omega t} - {\mathrm{i}}_2 \sin \mathrm{\omega t}. \mathrm{The} \mathrm{rms} \mathrm{current} \mathrm{is} \mathrm{given} \mathrm{by}$

  $\sqrt{\frac{{\mathrm{i}}_1^2 + {\mathrm{i}}_2^2}{2}}$

In a step-up transformer, the turn ratio is 1:2. A Leclanche cell (e.m.f. 1.5V) is connected across the primary coil. The voltage developed in the secondary coil would be-

Zero

A 220 V, 50 Hz ac source is connected to an inductance of 0.2 H and a resistance of 20 ohms in series. What is the current in the circuit :

  3.33A

$\mathrm{If} {\mathrm{X}}_{\mathrm{L}} = {\mathrm{X}}_{\mathrm{C}} \mathrm{then} \mathrm{the} \mathrm{reading} \mathrm{of} \mathrm{ideal} \mathrm{voltmeter} \mathrm{is}:$

  Zero

An electric motor operating on a 60 V dc supply draws a current of 10 A. If the efficiency of the motor is 50%, the resistance of its winding is 

3Ω

A step-down transformer is connected to 2400 volts line and 80 amperes of current is found to flow in output load. The ratio of the turns in primary and secondary coil is 20 : 1. If transformer efficiency is 100%, then the current flowing in primary coil will be 

4 A

A loss free transformer has 500 turns on its primary winding and 2500 in secondary. The meters of the secondary indicate 200 volts at 8 amperes under these conditions. The voltage and current in the primary is 

40 V, 40 A

A transformer connected to 220 Volt line shows an output of 2 A at 11000 Volt. The efficiency is 100%. The current drawn from the line is:

100 A

Orbital acceleration of electron is 

 $\frac{n^2{h}^2}{4{\mathrm{\pi }}^2{\mathrm{m}}^2{\mathrm{r}}^3}$   

which of the following is positively charged?

  $\mathrm{\alpha }-\mathrm{particles}$

The ratio of minimum to maximum wavelength in Balmer series is 

5 : 9           

Ionisation potential of hydrogen atom is 13.6 eV. Hydrogen atoms in the ground state are excited by monochromatic radiation of photon energy 12.1 eV. According to Bohr's theory, the spectral lines emitted by hydrogen will be:

three

The diagram shows the energy levels for an electron in a certain atom. Which transition shown represents the emission of a photon with the most energy?

III 

The kinetic energy of the electron in an orbit of radius r in the hydrogen atom is (e = electronic charge)

 $\frac{k{e}^2}{2r}$ 

Whenever a hydrogen atom emits a photon in the Balmer series:

it must emit another photon in the Lyman series.

The ionisation potential of hydrogen atom is

13.60 volt

Which source is associated with a line emission spectrum? 

Neon street Sign

Frequency of the series limit of Balmer series of hydrogen atom in terms of Rydberg constant R and velocity of light C is:

 $\frac{RC}{4}$

If a resistance coil is made by joining in parallel two resistances each of 20$\Omega$. An emf of 2V is applied across this coil for 100 seconds. The heat produced in the coil is

40 J

Which of the following graphs correctly represents the variation of mobility $\left(\mathrm{\mu }\right)$ of electrons with applied electric field (E) in a metallic conductor?

If I be the current limit of a fuse wire of length l and radius r, then select the appropriate relation

 $I \alpha l^0$

The resistance of platinum wire at 0$°\mathrm{C}$ is 22.05 $\mathrm{\Omega }$ and at 100$°\mathrm{C}$ it becomes 22.70 $\mathrm{\Omega }$. When the wire is heated to a temperature of t$°\mathrm{C}$ the resistance of wire becomes 24.91$\mathrm{\Omega }$. The value of t is 

  440

The sensitivity of a potentiometer can be increased by

  decreasing the current in the potentiometer wire

Masses of 3 wires of same metal are in the ratio 1 : 2 : 3 and their lengths are in the ratio 3 : 2 : 1. The electrical resistances are in ratio

27 : 6 : 1

A wire of radius r has resistance R. If it is stretched to a radius of $\frac{3r}{4}$, its resistance becomes 

$\frac{256R}{81}$

In the figure shown, the total resistance between A and B is

8 Ω

$\mathrm{In} \mathrm{the} \mathrm{circuit} \mathrm{shown} \mathrm{in} \mathrm{figure} \mathrm{if} \mathrm{power} \mathrm{dissipated} \mathrm{in} 9\mathrm{\Omega } \mathrm{resistor} \mathrm{is} 144\mathrm{W}, \mathrm{then} \mathrm{potential} \mathrm{difference} \mathrm{across} 3.6\mathrm{\Omega } \mathrm{resistor} \mathrm{will} \mathrm{be}$

  36V

A current of 1 mA is flowing through a copper wire. How many electrons will pass a given point in one second  $\left[\mathrm{e} = 1.6 \times {10}^{-19} \mathrm{Coulomb}\right]$

  $6.25 \times {10}^{15}$

If V be the accelerating voltage, then the maximum frequency of continuous x-rays is given by

  $\frac{eV}{h}$

The maximum kinetic energy of photoelectron emitted from the surface of work function f due to incidence of light of frequency n is E. If the frequency of incident light is doubled, then maximum kinetic of emitted photon will be

  2E + f

The de-Broglie wavelength associated with an electron accelerated through a voltage of 900 V is:

  $0.41 \stackrel{\mathrm{o}}{\mathrm{A}}$

The de-Broglie wavelength of a neutron in thermal equilibrium with heavy water at a temperature T (Kelvin) and mass m, is 

$\frac{h}{\sqrt{3mkT}}$

Electrons of mass m with de-Broglie wavelength $\lambda$ fall on the target in an X-ray tube. The cut off wavelength $\left({\lambda }_0\right)$ of the emitted X-ray is -

${\lambda }_0=\frac{2mc{\lambda }^2}{h}$         

Photons with energy 5 eV are incident on a cathode C in a photoelectric cell. The maximum energy of emitted photoelectrons is 2 eV. When photons of energy 6 eV are incident on C, no photoelectron will reach the anode A, if the stopping potential of A relative to C is

-3 V

When a metallic surface is illuminated with radiation of wavelength $\lambda$, the stopping potential is V. If the same surface is illuminated with radiation of wavelength 2$\lambda$, the stopping potential is $\frac{V}{4}$ .The threshold wavelength for metallic surface is:

() 3$\lambda$               

An electron of mass m and a photon have the same energy E. Find the ratio of de-Broglie wavelength associated with the electron to that associated with the photon. (c is the velocity of light)
^{$$\begin{gathered} 1. {\left(\frac{E}{2m}\right)}^{1/2} \\ 2. c{\left(2mE\right)}^{1/2} \\ 3. \frac{1}{c}{\left(\frac{2m}{E}\right)}^{1/2} \\ 4. \frac{1}{c}{\left(\frac{E}{2m}\right)}^{1/2} \end{gathered}$$}
 

A radiation of energy 'E' falls normally on a perfectly reflecting surface. The momentum transferred to the surface is (c=velocity of light)

A certain metallic surface is illuminated with monochromatic light of wavelength λ. The stopping potential for photoelectric current for this light is 3V_o. If the same surface is illuminated with light of wavelength 2λ. the stopping potential is V_o. The threshold wavelength for this surface for the photoelectric effect is:

Two charges each equal to 2μC are 0.5m apart. If both of them exist inside the vacuum, then the force between them is 

(3) 0.144 N

A cylinder of radius R and length L is placed in a uniform electric field E parallel to the cylinder axis. The outward flux over the surface of the cylinder is given by:

${\mathrm{\pi R}}^2\mathrm{E}$

The electric intensity due to an infinite cylinder of radius R and having charge q per unit length at a distance r(r > R) from its axis is 

Inversely proportional to r

The electric field in a certain region is acting radially outward and is given by E=Ar. A charge contained in a sphere of radius 'a' centered at the origin of the field will be given by

An electric dipole is in unstable equilibrium in the uniform electric field. The angle between its dipole moment and the electric field is

  180$°$

A particle having charge ${\mathrm{q}}_1$ exerts F electrostatic force on charge ${\mathrm{q}}_2$ at rest. If a particle having charge $\frac{q_1}{4}$ is placed midway between the line joining the two charges ${\mathrm{q}}_1 \mathrm{and} {\mathrm{q}}_2$ then electrostatic force on ${\mathrm{q}}_2$ due to ${\mathrm{q}}_1$ will become/remain

F

A charge q is to be divided on two small conducting spheres. What should be the value of charges on the spheres so that when placed at a certain distance apart, the repulsive force between them is maximum?

$\frac{q}{2} and \frac{q}{2}$

An electric dipole of dipole moment p is placed in an electric field of intensity E such that angle between electric field and dipole moment is $\theta$. Assuming that the potential energy of the dipole is zero when $\theta =0°$, the potential energy of the dipole will be

pE(1-cos$\theta$)

The electrostatic field due to a charged conductor just outside the conductor is 

normal to the surface at every point and zero inside the conductor

The law, governing the force between electric charges is known as 

Coulomb's law

The magnetic flux through a circuit of resistance R changes by an amount $\Delta \phi$ in time $\Delta t$, Then the total quantity of electric charge Q, which passing during this time through any point of the circuit is given by 

$Q=\frac{\Delta \varphi }{R}$

A coil of resistance 20$\Omega$ and inductance 5H has been connected to a 200 V battery. The maximum energy stored in the coil is

250 J

Lenz's law is a consequence of the law of conservation of 

Energy

If all linear dimensions of an inductor are tripled, then self-inductance will become (keeping the total number of turns per unit length constant)

  27 times

A metallic ring is attached to the wall of a room. When the north pole of a magnet is brought near to it, the induced current in the ring will be:

in the anticlockwise direction.

A coil having an area A₀ is placed in a magnetic field which changes from B₀ to 4B₀ in a time interval t. The e.m.f. induced in the coil will be 

$\frac{3A_0{B}_0}{t}$

A copper ring is held horizontally and a bar magnet is dropped through the ring with its length along the axis of the ring. The acceleration of the falling magnet while it is passing through the ring is-

Less than that due to gravity

A magnet is brought towards a coil (i) speedily (ii) slowly then the induced e.m.f./induced charge will be respectively 

More in first case/Equal in both case

As shown in the figure, a magnet is moved with a fast speed towards a coil at rest. Due to this induced electromotive force, induced current and induced charge in the coil is E, I, and Q respectively. If the speed of the magnet is doubled, the incorrect statement is 

Q increases

A coil having 500 square loops each of the side 10 cm is placed normal to a magnetic field which increases at the rate of 1.0 tesla/second. The induced e.m.f. in volts is 

5

The X-ray beam can be deflected by:

  None of these

In an electromagnetic wave in free space the root mean square value of the electric field is $E_{rms}=6$ V/m. The peak value of the magnetic field is:

 $2.83\times {10}^{-8}T$

Out of the following options which one can be used to produce a propagating electromagnetic wave?

An accelerating charge         

The energy of the EM wave is of the order of 15 KeV. To which part of the spectrum does it belong?

The electric field associated with an electromagnetic wave in vacuum is given by E= 40cos$\left(kz-6\times {10}^{8}t\right),$where E, z, and t are in volt/m, meter, and second respectively. The value of wave vector k is:

 $2 m^{-1}$                               

The ratio of the amplitude of the magnetic field to the amplitude of electric field for an electromagnetic wave propagating in vacuum is equal to

reciprocal of speed of light in vacuum

The electric and the magnetic field, associated with an electromagnetic wave, propagating along the +z-axis, can be represented by

   $\left[\mathrm{E}={\mathrm{E}}_0\hat{\mathrm{i}}, \mathrm{B}={\mathrm{B}}_{\mathrm{o}}\hat{\mathrm{j}}\right]$

The decreasing order of the wavelength of infrared, microwave, ultraviolet and gamma rays is

microwave, infrared, ultraviolet, gamma rays

Which of the following statements is false for the properties of electromagnetic waves?

Both electric and magnetic field vectors are parallel to each other and perpendicular to the direction of propagation of the wave

The electric field of an electromagnetic wave in free space is given by $\overrightarrow{\mathbf{E}}=10 \cos ({10}^{7}t+kx)\hat{\mathbf{j}} \mathrm{V}/\mathrm{m},$ where t and x are in seconds and meters respectively. It can be inferred that
1. The wavelength $\mathrm{\lambda }$ is 188.4 m.
2. The wave number k is 0.33 rad/m.
3. The wave amplitude is 10 V/m.
4. The wave is propagating along +x direction
Which one of the following pairs of statements is correct?

If W be the amount of heat produced in the process of charging an uncharged capacitor then the amount of energy stored in it is

W

A metallic sphere of capacitance $C_1$, charged to electric potential $V_1$ is connected by a metal wire to another metallic sphere of capacitance $C_2$ charged to electric potential $V_2$. The amount of heat produced in the connecting wire during the process is

$\frac{C_1{C}_2}{2(C_1+C_2)}{(V_1-V_2)}^2$

The electric potential at the surface of a charged solid sphere of insulator is 20V. The value of electric potential at its centre will be

  30V

The capacitance of a parallel plate capacitor is C. If a dielectric slab of thickness equal to one-fourth of the plate separation and dielectric constant K is inserted between the plates, then new capacitance become

 $\frac{4KC}{3K+1}$

The electric potential at a point at distance 'r' from a short dipole is proportional to

 $r^{-2}$

A hollow charged metal spherical shell has radius R. If the potential difference between its surface and a point at a distance 3R from the center is V, then the value of electric field intensity at a point at distance 4R from the center is

  $\frac{3\mathrm{V}}{32\mathrm{R}}$

Capacitors $C_1=10\mu F and C_2=30\mu F$ are connected in series across a source of emf 20KV. The potential difference across $C_1$ will be

15 KV

A hollow conducting sphere is placed in an electric field produced by a point charge placed at P as shown. Let $V_A,V_B,V_C$ be the potentials at points A, B and C respectively. Then

 $V_A=V_B=V_C$

Four particles each having charge q are placed at the vertices of a square of side a. The value of the electric potential at the midpoint of one of the side will be

  $\frac{1}{4\pi {ϵ}_0}\frac{2q}{a}(2+\frac{2}{\sqrt{5}})$

If E be the electric field inside a parallel plate capacitor due to Q and -Q charges on the two plates, then electrostatic force on plate having charge -Q due to the plate having charge +Q will be

 $\frac{-QE}{2}$

If the gravitational potential on the surface of the earth is V₀, then the potential at a point at a height equal to half of the radius of the earth is:

 $\frac{2}{3}{\mathrm{V}}_0$

The total mechanical energy of an object of mass m projected from the surface of the earth with escape speed is:

Zero

A body is thrown with a velocity equal to n times the escape velocity (v_e). The velocity of the body at a large distance away will be:

 ${\mathrm{v}}_{\mathrm{e}}\sqrt{{\mathrm{n}}^2-1}$

If g is the acceleration due to gravity on the earth's surface, the gain in the potential energy of an object of mass m raised from the surface of earth to a height equal to the radius of the earth R, is 

$\frac{1}{2}mgR$

Weightlessness experienced while orbiting the earth in space-ship is the result of

  Freefall towards the earth

A satellite is moving very close to a planet of density $\mathrm{\rho }$. The time period of the satellite is:

  $\sqrt{\frac{3\mathrm{\pi }}{\mathrm{\rho G}}}$

A projectile is fired upwards from the surface of the earth with a velocity ${\mathrm{kv}}_{\mathrm{e}}$ where ${\mathrm{v}}_{\mathrm{e}}$ is the escape velocity and k < 1. If r is the maximum distance from the center of the earth to which it rises and R is the radius of the earth, then r equals

  $\frac{\mathrm{R}}{1 - {\mathrm{k}}^2}$

The gravitational potential difference between the surface of a planet and 10 m above is 5 J/kg. If the gravitational field is supposed to be uniform, the work done in moving a 2 kg mass from the surface of the planet to a height of 8 m is

  8J

A planet is moving in an elliptical orbit. If T, V, E, and L stand, respectively, for its kinetic energy, gravitational potential energy, total energy and angular momentum about the center of the orbit, then

  E is always negative

In planetary motion, the areal velocity of the position vector of a planet depends on the angular velocity ($\omega$) and the distance of the planet from the sun (r). The correct relation for areal velocity is:

$\frac{dA}{dt} \alpha \omega r^2$

The variation of density (p) of gas with its absolute temperature (T) at constant pressure is best represented by the graph

An isolated system-

cannot transfer neither energy nor mass to or from the surroundings.

If the mean free path of atoms is doubled then the pressure of the gas will become:                                                                           

P/2           

A diatomic molecule has how many degrees of freedom-                                                                                             

A thermally insulated piston divides a container into two compartments.  Volume, temperature, and pressure in the right compartment are 2V, T and 2P, while in the left compartment the respective values are V, T and P.  If the piston can slide freely, then in the final equilibrium position, the volume of the right-hand compartment will be :

The graph which represents the variation of mean kinetic energy of molecules with temperature $t°C$ is ?

$V_{rms},V_{av},V_{mp}$ are root mean square, average and most probable speeds of molecules of a gas obeying Maxwellian velocity distribution. Which of the following statements is correct?

 $V_{rms}>V_{av}>V_{mp}$

Gas is found to obey the law $P^{2}V$ = constant. The initial temperature and volume are $T_0$ and $V_0$. If the gas expands to a volume $3V_0$, its final temperature becomes:

None of these

For a gas, the r.m.s speed at 800 K is:

Twice the value at 200 K

The average kinetic energy of a helium atom at $30°C$ is:                                                                                           [MP PMT 2004]

Less than 1 eV

Two bodies of equal masses revolve in circular orbits of radii R₁ and R₂ with the same period. Their centripetal forces are in the ratio

$\frac{R_1}{R_2}$

A body is imparted motion from rest to move in a straight line. If it is then obstructed by an opposite force, then:

The body is sure to slow down

For a rocket moving in free space, the fraction of mass to be disposed of Off to attain a speed equal to two times the exhaust speed is given by (given ${\mathrm{e}}^2$ = 7.4)

  0.86

The length of a spring is $l_1 and l_2$ when stretched with a force of 4 N and 5 N respectively. Its natural length is?

$5l_1-4l_2$

A simple pendulum hangs from the roof of a train moving on horizontal rails. If the string is inclined towards the front of the train, then train is-

In retarded motion

A lighter body and heavier body both are moving with same momentum and applied same retarding force. Their stoping distances are $s_1 and s_2$ respectively. Then the correct relation between $s_1 and s_2$-

 $s_1>s_2$

When a 5 kg plastic box is placed deep inside water, it accelerates at a rate of g/6. How much sand should be put inside the box so that it may accelerate down at the rate of g/6?

  2kg

Let $\theta$ denote the angular displacement of a simple pendulum oscillating in a vertical plane. If the mass of bob is m, the tension in the string is mgcos$\theta$-

  at extreme

The graph for stopping time (t) versus mass (m) is shown in the figure. Then which one of the pairs is given?

  Momentum, force

A metal ring of mass m and radius R is placed on smooth horizontal table and is set rotating about its own axis in such a way that each part of the ring moves with a speed v. Tension in the ring is:

 $\frac{m{v}^2}{2\mathrm{\pi }R}$

A magnet of magnetic moment M is situated with its axis along the direction of a magnetic field of strength B. The work done in rotating it by an angle of 180^o will be

+2MB

A magnetic needle suspended by a silk thread is vibrating in the earth's magnetic field. If the temperature of the needle is increased by 500°C, then

The time period increases

A magnetic needle is kept in a non-uniform magnetic field. It experiences:

A force and a torque

A long magnetic needle of length 2L, magnetic moment M and pole strength m units is broken into two pieces at the middle. The magnetic moment and pole strength of each piece will be:

 $\frac{M}{2},m$

Two identical thin bar magnets each of length l and pole strength m are placed at the right angle to each other with the north pole of one touching south pole of the other. The magnetic moment of the system is :

 $\sqrt{2}ml$

A bar magnet of length l and magnetic dipole moment M is bent to form an arc which subtends an angle of $120°$ at centre. The new magnetic dipole moment will be

  $\frac{3\sqrt{3}\mathrm{M}}{2\mathrm{\pi }}$

A small bar magnet is placed with its north pole facing the magnetic north pole. The neutral points are located at a distance r from its centre. If the magnet is rotated by 180^o, the neutral point shall be obtained at a distance of:

$$\begin{gathered} 1. 2\mathrm{r} \\ 2. \sqrt{2}\mathrm{r} \\ 3. 2^{-\frac{1}{3}}\mathrm{r} \\ 4. \frac{\mathrm{r}}{2\sqrt{2}} \end{gathered}$$

The unit of pole strength is:

Am

Magnetic field lines

All of these

Two small bar magnets are placed in the air at a distance r apart. The magnetic force between them is proportional to:

 $r^{-4}$

Two forces, 1 N and 2 N, act along with the lines x = 0 and y = 0. The equation of the line along which the resultant lies is given by:

  2y - x = 0

Component of $3\hat{i}+4\hat{j}$ perpendicular to $\hat{i}+\hat{j}$ and in the same plane as that of $3\hat{i}+4\hat{j}$ is:

 $\frac{1}{2}(\hat{j}-\hat{i})$

Given that $\overrightarrow{\mathrm{C} }= \overrightarrow{A } + \overrightarrow{B } \mathrm{and} \overrightarrow{\mathrm{C} }$ makes an angle $\mathrm{\alpha } \mathrm{with} \overrightarrow{\mathrm{A}} \mathrm{and} \mathrm{\beta } \mathrm{with} \overrightarrow{\mathrm{B}}$. Which of the following options is correct?

  $\mathrm{\alpha } <\mathrm{\beta }, \mathrm{if} \mathrm{A}>\mathrm{B}$

If the angle between the vector $\overrightarrow{A} and \overrightarrow{B}$ is  $\theta$, the value of the product $\left(\overrightarrow{B}\times \overrightarrow{A}\right).\overrightarrow{A}$ is equal to:

zero

Assertion: The graph between P and Q is a straight line when P/Q is constant.
Reason: The straight-line graph means that P is proportional to Q or P is equal to a constant multiplied by Q.

Which one, of the following statements, is correct?

Two forces of magnitude F have a resultant of the same magnitude F. The angle between the two forces is 

120°

Two forces with equal magnitudes F act on a body and the magnitude of the resultant force is F/3. The angle between the two forces is 

${\cos }^{-1}\left(-\frac{{\displaystyle 17}}{{\displaystyle 18}}\right)$

Two forces are such that the sum of their magnitudes is 18 N and their resultant is perpendicular to the smaller force and the magnitude of the resultant is 12 N. Then the magnitudes of the forces will be:

13 N, 5N

If two forces of 5 N each are acting along X and Y axes, then the magnitude and direction of resultant is 

$5\sqrt{2},\pi /4$

If the magnitude of the sum of two vectors is equal to the magnitude of the difference of the two vectors, the angle between these vectors is:

 $$\begin{gathered} 1. 0^0 \\ 2. {90}^0 \\ 3. {45}^0 \\ 4. {180}^0 \end{gathered}$$

A closed rectangular tank is completely filled with water and is accelerated horizontally with an acceleration a towards right. Pressure is (i) maximum at, and (ii) minimum at

(i) B (ii) D

8000 identical water drops are combined to form a big drop. Then the ratio of the final surface energy to the initial surface energy of all the drops together is 

1 : 20                     

Water flows through a frictionless duct with a cross-section varying as shown in the figure. Pressure p at points along the axis is represented by
                      

A body of density ${\mathrm{d}}_1$ is counterpoised by Mg of weights of density ${\mathrm{d}}_2$ in air of density d. Then the true mass of the body is

 $\frac{\mathrm{M}(1-\mathrm{d}/{\mathrm{d}}_2)}{(1-\mathrm{d}/{\mathrm{d}}_1)}$

A tube of length L is filled completely with an incompressible liquid of mass M and closed at both ends. The tube is then rotated in a horizontal plane about one of its ends with a uniform angular velocity $\omega$. The force exerted by liquid at the other end is

  $\frac{{\mathrm{M\omega }}^2\mathrm{L}}{2}$

The radius of a soap bubble is increased from R to 2 R. Work done in this process (T = surface tension) is:

  $24 {\mathrm{\pi R}}^2\mathrm{T}$

The flow rate from a tap of diameter 1.25 cm is 3 lit/min. The coefficient of viscosity of water is ${10}^{-3}$ Pas. The nature of flow is :

Turbulent

A small spherical solid ball is dropped in a viscous liquid. Its journey in the liquid is best described in the figure by :

  Curve C

The value of g at a place decreases by 2%. The barometric height of mercury

The area of cross-section of the wider tube shown in the figure is $800 {\mathrm{cm}}^2.$ If a mass of 12 kg is placed on the massless piston, then the difference in heights h of the levels of water in the two tubes will be:

  15 cm

A gas undergoes a process in which its pressure P and volume V are related as ${\mathrm{VP}}^{\mathrm{n}}=\mathrm{constant}$. The bulk modulus for the gas in the process is:

[This question includes concepts from Kinetic Theory chapter]

$\frac{P}{n}$

The Young's modulus of a wire of length 'L' and radius 'r' is 'Y'. If length is reduced to L/2 and radius r/2, then Young's modulus will be 

Y

Three wires A, B, C made of the same material and radius have different lengths. The graphs in the figure show the elongation-load variation. The longest wire is
       

C

The breaking stress of a wire depends upon:

material of the wire.

The bulk modulus of a spherical object is B. If it is subjected to uniform pressure P, the fractional decrease in radius will be:

 $\frac{P}{3B}$

The Young's modulus of steel is twice that of brass. Two wires of the same length and of the same area of cross-section, one of steel and another of brass are suspended from the same roof. If we want the lower ends of the wires to be at the same level, then the weight added to the steel and brass wires must be in the ratio of:

2:1

The following four wires are made of the same material. Which of them will have the largest extension when the same tension is applied?

When a certain weight is suspended from a long uniform wire, its length increases by one cm. If the same weight is suspended from another wire of the same material and length but having a diameter half of the first one, then the increase in length will be -

4 cm                                 

The material which practically does not show elastic after effect is 

Quartz

A force F is needed to break a copper wire having radius R. The force needed to break a copper wire of radius 2R will be:

A ball rolls off top of a staircase with a horizontal velocity u m/s. If the steps are h metre high and b mere wide, the ball will just hit the edge of nth step if n equals to

 $\frac{2h{u}^2}{g{b}^2}$

A man standing on the roof of a house of height h throws one particle vertically downwards and another particle horizontally with the same velocity u. The ratio of their velocities when they reach the earth’s surface will be

1:1

Path of a projectile with respect to another projectile so long as both remain in the air is:

Straight

A man weighing 80 kg is standing in a trolley weighing 320 kg. The trolley is resting on frictionless horizontal rails. If the man starts walking on the trolley with a speed of 1 m/s, then after 4 sec his displacement relative to the ground will be

3.2 m

A particle is projected at an angle $\theta$ with horizontal with an initital speed u. When it makes an angle $\alpha$ with horizontal, its speed v is-

 $\frac{u\cos \theta }{\cos \alpha }$

A particle is moving along the path y = ${\mathrm{x}}^2$ from x = 0 m to x = 2 m. Then the distance traveled by the particle is:

  $>\sqrt{20} \mathrm{m}$

Six particles situated at the corners of a regular hexagon of side 'a' move at constant speed v. Each particle maintains a direction towards the particle at the next. The time which the particles will take to meet each other is-

  $\frac{2\mathrm{a}}{\mathrm{v}} \sec$

A body is projected with velocity $20\sqrt{3}$ m/s with an angle of projection 60$°$ with horizontal. Calculate velocity on that point where body makes an angle 30$°$ with the horizontal.

20 m/s

In a uniform circular motion, which of the following quantity is not constant

Momentum

A particle is moving with veocity $\overrightarrow{\mathrm{v}}=\mathrm{k}(\mathrm{y}\hat{\mathrm{i}}+\mathrm{x}\hat{\mathrm{j}})$; where k is constant. The general equation for the path is:

 ${\mathrm{y}}^2={\mathrm{x}}^2+\mathrm{constant}$

A ball is thrown upward with a certain speed. It passes through the same point at 3 second and 7 second from the start. The maximum height achieved by the ball is:

  125 m

For the following acceleration versus time graph the corresponding velocity versus displacement graph is 

The displacement x of a particle moving in one dimension under the action of a constant force is related to time t by the equation $t = \sqrt{x} + 3$, where x is in meters and t is in seconds. What is the displacement of the particle from t = 0 s to t = 6 s?

  0

The acceleration a (in ${\mathrm{ms}}^{-2}$) of a body, starting from rest varies with time t(in s) following the equation a = 3t+4. The velocity of the body at time t = 2s will be :

14 ${\mathrm{ms}}^{-1}$

A body thrown vertically so as to reach its maximum height in t second. The total time from the time of projection to reach a point at half of its maximum height while returning (in second) is:

 $\left(1+\frac{1}{\sqrt{2}}\right)t$

A stone falls freely from rest from a height h and it travels a distance $\frac{9h}{25}$ in the last second. The value of h is:

125 m

A point moves in a straight line under the retardation a${\mathrm{v}}^2$. If the initial velocity is u, the distance covered in 't' seconds is-

  $\frac{1}{\mathrm{a}}\ln \left(1+\mathrm{aut}\right)$

A particle is thrown upwards from ground. It experiences a constant resistance force which can produce retardation of 2 $m/s^2$. The ratio of time of ascent to the time of descent is: $[g=10 m/s^2]$

 $\sqrt{\frac{2}{3}}$

A bullet loses $\frac{1}{20}$ of its velocity passing through a plank. The least number of planks required to stop the bullet is (All planks offers same retardation)

11

A body starts from the origin and moves along the X-axis such that the velocity at any instant is given by $(4t^3-2t)$, where t is in sec and velocity in m/s. What is the acceleration of the particle, when it is 2 m from the origin ?

22 m/s²

When a 12 Ω resistor is connected in parallel with a moving coil galvanometer then its deflection reduces from 50 divisions to 10 divisions. The resistance of the galvanometer is:

48 Ω

A voltmeter has a resistance of G ohms and range V volts. The value of resistance used in series to convert it into a voltmeter of range nV volts is :

$(n-1)G$

Which of the following statement is wrong:

Ammeter is placed in parallel across the conductor in a circuit

The dots in the figure show a magnetic field perpendicular to the plane of the paper and coming out of it. The curve ABC shows the trajectory of a particle in the plane of the paper. What is a particle?

  Proton

A long solenoid has 800 turns per meter length of the solenoid. A current of 1.6 A flows through it. The magnetic induction at the end of the solenoid on its axis is:

  $8\times {10}^{-4} \mathrm{T}$

The unit of reduction factor of the tangent galvanometer is 

Ampere

In order to pass 10% of the main current through a moving coil galvanometer of 99 ohms, the resistance of the required shunt is :

11 Ω

A current-carrying closed Loop in the form of a right isosceles triangle ABC is placed in xy plane in a uniform magnetic field acting along the y-axis as shown in the figure. If the magnetic force on the arm AC is $\overrightarrow{F}$, then force on the arm BC and AB are respectively

 $-\overrightarrow{F} and zero$

A uniform electric field and a uniform magnetic field are acting in the same direction in a certain region. If a proton is projected in this region such that its velocity is pointed along the direction of fields, then the proton :

  will speed up

When a proton is released from rest in a room, it starts with an initial acceleration ${\mathrm{a}}_0$ towards the east. When it is projected towards the north with a speed ${\mathrm{v}}_0$, it moves with initial acceleration $3{\mathrm{a}}_0$ towards east. The electric and magnetic fields in the room are -

  $\frac{{\mathrm{Ma}}_0}{\mathrm{e}}\mathrm{east}, \frac{2{\mathrm{Ma}}_0}{{\mathrm{ev}}_0}up$

Atoms having different atomic number as well as different mass number but having same number of neutrons 

isotones

In a radioactive substance at t = 0, the number of atoms is 8$\times {10}^4$, its half-life period is 3 yr. The number of atoms equal to $1\times {10}^4$ will remain after an interval of:
[UP CPMT 2010]

9 yr

What is the respective number of $\alpha$ and $\beta$-particles emitted in the following radioactive decay?

$X_{90}^{{}_{200}}\to {}_{}Y_{80}^{168}$ 

8 and 6   

The half-life of radium is 1622 years. How long will it take for seven-eighth of a given amount of radium to decay

4866 years

The mass of a proton is 1.0073 u and that of the neutron is 1.0087 u (u = atomic mass unit) The binding energy of ${}_{2}H{e}^4$ is (mass of helium nucleus = 4.0015 u)

28.4 MeV

The binding energies of the nuclei A and B are $E_a and E_b$ respectively. Three atoms of the element B fuse to give one atom of element A and an energy Q is released. Then $E_a, E_b$ and Q are related as:

 $E_a-3E_b=Q$ 

A free neutron decays into a proton, an electron and:

an antineutrino.

In a radioactive sample the fraction of initial number of radioactive nuclei, which remains undecayed after n mean lives is 

 $\frac{1}{e^n}$ 

The activity of a radioactive sample is measured as 9750 counts/min at t = 0 and as 975 counts/min at t = 5 min. The decay constant is approximately:

0.461/min           

The energy equivalent of one atomic mass unit is:

931 MeV 

The motion of a particle varies with time according to the relation $\mathrm{y} =\mathrm{a} \sin \mathrm{\omega t}+\mathrm{a} \cos \mathrm{\omega t}$. Then

  The motion is SHM with an amplitude $a\sqrt{2}$

If a particle is executing SHM, with an amplitude A, the distance moved and the displacement of the body in a time equal to its time period are, respectively, 

  4A, 0

The variation of acceleration of a particle executing SHM with displacement x is:

A particle is subjected to two simple harmonic motions in the same direction having equal amplitudes and equal frequency. If the resulting amplitude is equal to the amplitude of individual motions, the phase difference between them will be

  $\frac{2\mathrm{\pi }}{3}$

The equations of the displacement of two particles making SHM are represented by y₁ = a sin (ωt + φ) and y₂ = a cos (ωt) respectively. The phase difference of the velocities of the two particles will be

 The displacement of a particle executing SHM is given by y = 0.25 (sin 200t) cm. The maximum speed of the particles is:

  50 cm/sec

Which of the following figure represents damped harmonic motion?
(i)
(ii)
(iii)
(iv)

  (i) and  (iv)

A particle is executing SHM with an amplitude A and the time period T. If at t = 0, the particle is at origin (mean position), then the time instant when it covers a distance equal to 2.5A will be

  $\frac{7\mathrm{T}}{12}$

The time period of a spring mass system at the surface of earth is 2 second. What will be the time period of this system on the moon where acceleration due to gravity is $\frac{1}{6}\mathrm{th}$ of the value of g on earth's surface?

  $2 \mathrm{seconds}$

A particle undergoes SHM with a time period of 2 seconds. In how much time will it travel from its mean position to a displacement equal to half of its amplitude?

 $\frac{1}{6}s$

Which of the following is not due to the total internal reflection of light

  Difference between real and apparent depth of a pound

A ray of light incident on an equilateral prism at grazing incidence emerges from the prism at grazing emergence. The Refractive index of the prism is

2

Absolute refractive indices of glass and water are 3/2 and 4/3. The ratio of velocity of light in glass and water will be

  8:9

Two identical equiconvex thin lenses each of focal lengths 20 cm, made of material of refractive index 1.5 are placed coaxially in contact as shown. Now, the space between them is filled with a liquid with a refractive index of 1.5. The equivalent power of this arrangement will be:

+5 D

The length of an astronomical telescope adjusted for parallel light is 90 cm. If the magnifying power of the telescope is 17, then the focal length of eyepiece and objective are respectively

5 cm and 85 cm

A ray of light falls on a transparent sphere as shown in the figure. If the final ray emerges from the sphere parallel to the horizontal diameter, then calculate the refractive index of the sphere. Consider that the sphere is kept in the air.
                                           

  $\sqrt{3}$

A point source of light B is placed at a distance L in front of the centre of a mirror of width d hung vertically on a wall. A man walks in front of the mirror along a line parallel to the mirror at a distance 2L from it as shown. The greatest distance over which he can see the image of the light source in the mirror is

3d

Two plane mirrors, A and B are aligned parallel to each other, as shown in the figure. A light ray is incident at an angle of $30°$ at a point just inside one end of A. The plane of incidence coincides with the plane of the figure. The maximum number of times the ray undergoes reflections (excluding the first one) before it emerges out is :
                      

  30

A concave mirror of focal length 100 cm is used to obtain the image of the sun which subtends an angle of $\mathrm{30\text{'}}$. The diameter of the image of the sun will be:

(2) $0.87cm$

A square of side 3 cm  is placed at a distance of 25 cm from a concave mirror of focal length 10 cm. The centre of the square is at the axis of the mirror and the plane is normal to the axis. The area enclosed by the image of the square is

$4 c{m}^2$                        

The PN junction diode is used as

A rectifier

The emitter-base junction of a transistor is …… biased while the collector-base junction is ……. biased.

forward, reverse

In an NPN transistor the collector current is 24 mA. If 80% of electrons reach collector its base current in mA is

When a p-n junction is forward biased, then:

  the p-side is at a higher potential than n side.

When a transistor is used as a switch it is in:

  Both cut off state and saturation state are possible

Which of the following is correct for n-type semiconductor?

  Electrons are majority carriers and pentavalent atoms are dopants.

The combination of ‘NAND’ gates shown here under (figure) are equivalent to

An OR gate and an AND gate respectively

The input resistance of a silicon transistor is

100 $\mathrm{\Omega }$. Base current is changed by 40 $\mathrm{\mu A}$

which results in a change in collector current

by 2 mA. This transistor is used as a common-

emitter amplifier with a load resistance of 4 k$\mathrm{\Omega }$.

The voltage gain of the amplifier is

2000

The following configuration of the logic gate is equivalent to

  XOR gate

Three ideal diodes are connected to the battery as shown in the circuit. The current supplied by the battery is

  2A

A small mass attached to a string rotates on a frictionless table top as shown. If the tension on the string is increased by pulling the string causing the radius of the circular motion to decrease by a factor of 2, the kinetic energy of the mass will

Increase by a factor of 4                                       

Three-point masses 'm' each, are placed at the vertices of an equilateral triangle of side a. Moment of inertia of the system about axis COD is-

 $\frac{5}{4}m{a}^2$

A particle is moving in a circular orbit with constant speed. Select wrong alternate

Its linear momentum is conserved

An ABC is a right-angled triangular plate of uniform thickness. The sides are such that AB > BC. As shown in the figure \(I_1,I_2\)  and \(I_3\) are moments of inertia about AB, BC and AC respectively. Which of the following relation is correct?

One solid sphere A and another hollow sphere B are of same mass and same outer radii. Their moment of inertia about their diameters are respectively I_A and I_B such that

 ${\mathrm{I}}_{\mathrm{A}}<{\mathrm{I}}_{\mathrm{B}}$

A couple produces:                                                               [NTSE 1995; CBSE PMT 1997; DCE 2004]

Purely rotational motion

A particle of mass 1 kg is kept at (1m, 1m, 1m). The moment of inertia of this particle about z-axis would be

  $2 \mathrm{kg}-{\mathrm{m}}^2$

One quarter sector is cut from a uniform circular disc of radius R.  This sector has mass M.  It is made to rotate about a line perpendicular to its plane and passing through the centre of the original disc.  Its moment of inertia about the axis of rotation is [IIT-JEE (Screening) 2001]

 $\frac{1}{2}M{R}^2$

A wheel is rotating at the rate of 33 rev/min.  If it comes to stop in 20 s. Then, the angular retardation will be

 $\frac{11\mathrm{\pi }}{200} rad/s^2$

A ball hits the floor and rebounds after an inelastic collision. In this case

  the total momentum of the ball and the earth is conserved

Heat current is maximum in which of the following (rods are of identical dimension) ?

One kilogram of ice at $0°$C is mixed with one kilogram of water at 80$°C$. The final temperature of the mixture is (Take: Specific heat of water = 4200 J $k{g}^{-1}{C}^{-1}$, Latent heat of ice = 336 kJ $k{g}^{-1}$)

 $0°$C             

The fastest mode of heat transfer is 

  Radiation

A temperature of 100 ^oF (Fahrenheit scale) is equal to T K (Kelvin scale). The value of T is:

  310.9

A black body at temperature 300K radiates heat at the rate E. If its temperature is increased by 600K, the rate of radiation will increase to -

  81E

A body cools down from $80°\mathrm{C} \mathrm{to} 70°\mathrm{C}$ in 5 minutes. The temperature of the same body will fall from $70°\mathrm{C} \mathrm{to} 60°\mathrm{C}$ in:

  more than 5 minutes.

If ${\lambda }_m$ is the wavelength, corresponding to which the radiant intensity of a block is at its maximum and its absolute temperature is T, then which of the following graph correctly represents the variation of T.

Heat capacity is equal to the product of:

  mass and specific heat

When a block of iron floats in Hg at $0°C$, a fraction $K_1$ of its volumen= is submerged, while at temperature of $60°C$ a fraction $K_2$ is seen to be submersed. If the coefficient of volume expansion of iron is ${\gamma }_{Fe}$ and that of mercury is ${\gamma }_{Hg}$, then the ratio $\frac{K_1}{K_2}$ can be expressed as:

 $\frac{1+60{\gamma }_{Fe}}{1+60{\gamma }_{Hg}}$

Hot water cools from 60$°\mathrm{C}$ to 50$°\mathrm{C}$ in first 10 minutes and from 50$°\mathrm{C}$ to 42$°\mathrm{C}$ in next 10 minutes. The temperature of surrounding is :

  $10° \mathrm{C}$

One femtometer is equivalent to

${10}^{-15}m$

If the unit of length and force be increased four times, then the unit of energy is 

Increased 16 times

Ampere - hour is a unit of 

Quantity of electricity

The unit of specific resistance is 

Ohm - cm

The binding energy of a nucleon in a nucleus is of the order of a few 

MeV

Parsec is a unit of :

Distance

The unit of Planck's constant is:

Joule-s

Number of base SI units is

7

SI unit of permittivity is:

$C^2{m}^{-2}{N}^{-1}$

Which does not has the same unit as others

J-sec

An unpolarised light incident on polariser has amplitude A and the angle between analyzer and polariser is 60°. Light transmitted by analyzer has an amplitude:

 $A/2\sqrt{2}$

In Young's double-slit experiment, the intensity at a point is (1/4) of the maximum intensity. The angular position of this point is:

sin^-1(λ/3d)

Two waves of intensity ratio 9:1 interfere to produce fringes in a young's double-slit experiment, the ratio of  intensity at maxima  to the intensity at minima is

  4:1

Two polaroids $P_1 and P_2$ are placed with their axis perpendicular to each other. Unpolarised light $I_o$ is incident on $P_1$. A third polaroid $P_3$ is kept in between $P_1 and P_2$ such that its axis makes an angle ${45}^{°}$ with that of $P_1$. The intensity of transmitted light through $P_2$

() $\frac{I_o}{8}$

The interference pattern is obtained with two coherent light sources of intensity ratio n. In the interference pattern, the ratio $\frac{I_{max}-I_{min}}{I_{max}+I_{min}}$ will be

 $\frac{2\sqrt{n}}{n+1}$

A linear aperture whose width is 0.02 cm is placed immediately in front of a lens of focal length 60 cm. The aperture is illuminated normally by a parallel beam of wavelength $5\times {10}^{-5}$ cm. The distance of the first dark band of the diffraction pattern from the centre of the screen is

0.15 cm

The intensity at the maximum in Young's double-slit experiment is ${\mathrm{I}}_0$ when the distance between two slits is d=5$\lambda$, where $\lambda$ is the wavelength of light used in the experiment. What will be the intensity in front of one of the slits on the screen placed at a distance D= 10 d?

 $\frac{{\mathrm{I}}_0}{2}$             

In a diffraction pattern due to a single slit of width a,the first minimum is observed at an angle ${30}^{\circ }$ when light of wavelength 5000 $\dot{A}$ is incident on the slit. The first secondary maximum is observed at an angle of 

(a) ${\sin }^{-1}\left(\frac{2}{3}\right)$           (b) ${\sin }^{-1}\left(\frac{1}{2}\right)$

(c) ${\sin }^{-1}\left(\frac{3}{4}\right)$           (d) ${\sin }^{-1}\left(\frac{1}{4}\right)$

For a parallel beam of monochromatic light of wavelength diffraction is produced by a single slit whose width 'a' is of the order of the wavelength of the light. If 'D' is the distance of the screen from the slit, the width of the central maxima will be
(1)2Dλ/a

(2)Dλ/a

(3)Da/λ

(4)2Da/λ

In a double-slit experiment, the two slits are 1 mm apart and the screen is placed 1 m away. A monochromatic light of wavelength 500 nm is used. What will be the width of each slit for obtaining ten maxima of double-slit within the central maxima of a single-slit pattern?

0.2 mm

At what temperature velocity of sound is double than that of at 0°C 

819°C

The phase difference between two points separated by 1m in a wave of frequency 120 Hz is 90°. The wave velocity is :

480 m/s

If velocity of sound in a gas is 360 m/s and the distance between a compression and the nearest rarefaction is 1m, then the frequency of sound is 

180 Hz

How many degrees of freedom the gas molecules have if, under STP, the gas density $\rho =1.3 kg/m^3$ and the velocity of sound propagation in it is 330 m$s^{-1}$?

5         

Equation of the wave is given by y = 0.4 sin(314t - 3.14x), where x and y are in meter and t is in second. The speed of the wave is :

  100 m/s

A plane progressive wave cannot be represented by

  $\mathrm{y} = \mathrm{A} \log \mathrm{x} + \mathrm{B} \log \mathrm{x}$

The phase difference between the prongs of a tuning fork is :

  $\mathrm{\pi }$

The isothermal elasticity of a medium is ${\mathrm{E}}_{\mathrm{i}}$ and the adiabatic elasticity in ${\mathrm{E}}_{\mathrm{a}}$. The velocity of sound in the medium is proportional to

  $\sqrt{{\mathrm{E}}_{\mathrm{a}}}$

When a wave is reflected from a denser medium the change in phase is :

  $\mathrm{\pi }$

In a stationary wave along a string, the strain is :

  maximum at the nodes

A spring 40 mm long is stretched by the application of a force. If 10 N force required to stretch the spring through 1 mm, then work done in stretching the spring through 40 mm is

8J

Two springs with spring constants $k_1$ = 1500 N/m and $k_2$ = 3000 N/m are stretched by the same force. The ratio of potential energy stored in the springs will be 

2:1

A block of mass 2 kg moving with velocity of 10 m/s on a smooth surface hits a spring of force constant $80\times {10}^3$ N/m as shown. The maximum compression in the spring is

5 cm

A body starts moving from rest in straight line under a constant power source. Its displacement in time t is proportional to

 $t^{3/2}$

A block of mass m = 25 kg on a smooth horizontal surface with a velocity $\overrightarrow{v}$ =3 $m{s}^{-1}$ meets the spring of spring constant k = 100 N/m fixed at one end as shown in the figure. The maximum compression of the spring and velocity of the block as it returns to the original position respectively are: 

  1.5 m, -3 $m{s}^{-1}$

The velocity, given to the block of mass (m), is $\sqrt{\frac{7}{2}gl}$to rotate it in a circle of radius l. Calculate the height (h) where the block leaves the circle.

 $\frac{3l}{2}$

A spring of force constant 800 N/m has an extension of 5cm. The work done in extending it from 5cm to 15 cm is:

8 J

If length of string is $l\mathit{ }\mathit{=}\mathit{ }\frac{\mathit{10}}{\mathit{3}}m\mathit{,}\mathit{ }\frac{{\mathit{T}}_{\mathit{m}\mathit{a}\mathit{x}}}{{\mathit{T}}_{\mathit{m}\mathit{i}\mathit{n}}}\mathit{=}\mathit{4}$

$$\begin{gathered} \mathrm{where} \\ {\mathrm{T}}_{\max }= \mathrm{Maximum} \mathrm{tension} \mathrm{in} \mathrm{the} \mathrm{string} \\ {\mathrm{T}}_{\min }=M\mathrm{inimum} \mathrm{tension} in \mathrm{the} \mathrm{string}. \\ \mathrm{Velocity} \mathrm{at} \mathrm{highest} \mathrm{point} \mathrm{is} - \end{gathered}$$

  10 m/s

The relation between velocity (v) and time (t) is $v\propto \sqrt{\mathrm{t}}$, then which one of the following quantity is constant?

  Power

A particle is moving on the circular path of the radius (R) with centripetal acceleration $a_c=k^{2}R{t}^2$. Then the correct relation showing power (P) delivered by net force versus time (t) is 

3