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CBSE Questions for Class 12 Medical Physics Electric Charges And Fields Quiz 13 - MCQExams.com

The potential at a point (x,0,0) is given by V=(1000x+1500x2+500x3). The intensity of the electric field at x=1 will be
  • 550V/m
  • 55V/m
  • 55000V/m
  • 5500V/m
Four changed particles, each having a charge q, are placed at the four vertices of a regular pentagon. The sides of the Pentagon have equal length 'a'. The electric field at the centre of the Pentagon is :
1016438_5a6ab6107d9d45aeb4ce38c54b39ac0f.PNG
  • q4πε0a
  • 2q4πε0a2
  • q4πε0a2
  • None of these
An electron is projected from a distance d and with initial velocity u parallel to a uniformly charged flat conducting plate as shown. It strikes the plate after travelling a distance \ell along the direction of projection. The surface charge density of the conducting plate is equal to
1017274_126cd76ba16d457f8f98e47260744633.PNG
  • \dfrac{2d\varepsilon_0mu^2}{e\ell^2}
  • \dfrac{2d\varepsilon_0mu}{e\ell^2}
  • \dfrac{d\varepsilon_0mu^2}{e\ell}
  • \dfrac{d\varepsilon_0mu}{e\ell}
An ionized gas contains both positive and negative ions. If it is subjected simultaneously to an electric field along the +x direction and a magnetic field along the z-direction, then.
  • Positive ions deflects towards +y-direction and negative ions towards -y direction
  • All ions deflect towards +y -direction
  • All ions deflect towards -y direction
  • Positive ions deflect towards -y direction and negative ions towards y-direction
Six point charges are kept at the vertices of a regular hexagon of side L and centre O, as shown in the figure. Given that \dfrac { 1 }{ 4\pi { \varepsilon  }_{ 0 } } \dfrac { q }{ { L }^{ 2 } }, which of the following statement(s) is(are) correct?
1011069_4fa8c98a1f374001b370686801531ee9.png
  • The electric field at O is 6K along OD.
  • The potential at O is zero.
  • The potential at all points on the line PR is zero.
  • The potential at all points on the line ST is same.
Fill in the blanks.
A field normal to the plane of a circular wire n turns and radius r which carries a current I is measured on the axis of the coil at small h distance h from the centre of the coil. This is smaller than the field at the centre by a friction ____
  • 3\dfrac{3h^2}{2r^2}
  • \dfrac{h^2}{2r^2}
  • \dfrac{4h^2}{2r^2}
  • \dfrac{3h^2}{2r^2}
A "dipole" is formed from a rod of length 2 a and two charges +q and -q. Two such dipoles are oriented as shown in figure, their centers being separated by the distance R. The force exerted on the left dipole is         . 
1018729_a1630b0b24cd486da142779428b99b07.png
  • \dfrac{6kP_1P_2}{r^4}
  • \dfrac{3kP_1P_2}{r^4}
  • \dfrac{2kP_1P_2}{r^4}
  • \dfrac{4kP_1P_2}{r^4}

Two identical conducting spheres M and N has charges {q_m} and {q_n} respectively. A third identical neutral sphere P is brought in contact with M and then separated. Now sphere P is brought in contact with N and then separated. Final charge on sphere P will be:

  • \dfrac{q_m + 2q_n}{6}
  • \dfrac{q_m + q_n}{4}
  • {q_m}\dfrac{ q_n}{4}
  • \dfrac{q_m + 2q_n}{4}
An elliptical cavity is charge within perfect conductors. A positive charge q is placed at the centre of the cavity. The points A and B are on the cavity surface as shown, Then:
1031264_b4d281148ef44cdd983bfc01cb8126f7.png
  • Electric field near A in the cavity = electric field near B in the cavity.
  • Charge density at A= charge density at B.
  • Potential at A= potential at B.
  • Total electric field flux through the surface of the cavity is q/\ \varepsilon_{0}
A charge of 1 \mu C is divided into two parts such that their charges are in the ratio of 1:3 . These two charges are kept at distance 1m apart in vacuum. Then, the electric force between them (in newton) is :
  • 1.7 \times 10^{-3}
  • 1.7 \times 10^{-4}
  • 3.4\times 10^{-3}
  • 3.4\times 10^{-5}
Consider a hemispherical surface of radius r, a positive point charge q is kept at the centre of hemisphere. The electric flux through this hemisphere is :
  • zero
  • \dfrac{q}{\varepsilon_0}
  • \dfrac{q}{2\varepsilon_0}
  • \dfrac{2q}{\varepsilon_0}
A thin non-conducting ring of radius R has a linear charge \lambda = \lambda_0 \cos \theta where \lambda_0 is the value of \lambda at \theta = 0 . The net electric dipole moment for this charge distribution is :
1034018_36e72dd019bd4c45a94d383c0110ad4f.JPG
  • \pi R^2 / \lambda_0
  • \lambda_0 / \pi R^2
  • \pi R^2 \lambda_0
  • \dfrac {\lambda_0 \pi}{ R^2}
A particle of mass m and charge q at rest is released in a uniform electric field between parallel planes of charge +q and -q respectively. The particle accelerates towards the other place a distance 'd' away. The speed at which it strikes the opposite plane is:
  • \sqrt{qEd/m} and j
  • \sqrt{2qEd/m} along -j
  • \sqrt{qm/Ed} along j
  • \sqrt{qm/Ed} along -j
The diode moment of a system of charge +q distributed uniformly on an arc of radius R subtending an angle \pi/2 at its centre where another charge -q is placed is:
  • \frac{2\sqrt{2} qR}{\pi}
  • \frac{\sqrt{2} qR}{\pi}
  • \frac{qR}{\pi}
  • \frac{2qR}{\pi}
Electric field at a distance 4R from the surface of a charge cylinder is E . If R is the radius of the cylinder and L is the length of the cylinder then surface charge density of the cylinder is:
  • \dfrac { 4 \epsilon E }{L}
  • \dfrac { 5 \epsilon E }{L}
  • 5 \epsilon E
  • 4 \epsilon E
A cubical region of side 'a' has its centre at the origin. It encloses three fixed point charges, -q at (0, -a/4, 0), +3q at (0, 0, 0) and -q at (0, +a/4, 0). Choose the incorrect option
1063340_584627db5208471e8fcfd04be12c1c04.jpg
  • The net electric flux crossing the plane x = + \dfrac {a}{2} is equal to the net electric flux crossing the plane x = -\dfrac {a}{2}
  • The net electric flux crossing the plane y = +\dfrac {a}{2} is more than the net electric flux crossing the plane y = -\dfrac {a}{2}
  • The net electric flux crossing the entire region is \dfrac {q}{\epsilon_{0}}
  • The net electric flux crossing the plane z = \dfrac {a}{2} is equal to the net electric flux crossing the plane x = + \dfrac {a}{2}
An electric dipole is kept on the axis of a uniformly charged ring at distance \sqrt 2 R from the centre of  the ring. The direction of the dipole moment is along the axis. the dipole moment is P, charge of the ring  is Q and radius of the ring is R. The force on the dipole is:
  • \dfrac{4 k p Q}{3 \sqrt 3 R^S}
  • \dfrac{k p Q}{3 \sqrt 3 R^S}
  • \dfrac{2 k p Q}{3 \sqrt 3 R^S}
  • Zero
A square surface of side L metre in the plane of the paper is placed in a uniform electric field E(V/m) acting along the same place at an angle \theta with the horizontal side of the square as shown in figure. The electric flux linked to the surface in unit of V-m, is
1113045_034046dbb7934a18ad9e49d401eadac6.png
  • EL^{2}
  • EL^{2}\cos \theta
  • EL^{2}\sin \theta
  • Zero
A negative charged object reples another charged object kept close to it. What is the nature of the charge on the other object?
  • positive
  • negative
  • both
  • none.
electric intensity in axis of dipole at dist. 2m from its centre is 9\times 10^{3}\ N/C. Electric dipole moment of dipole is
  • 4\times 10^{-6}\ cm
  • 8\times 10^{-6}\ cm
  • 2\times 10^{-6}\ cm
  • 16\times 10^{-6}\ cm
A square loop of side b is rotating with angular speed \omega about one of the diagonals as axis. At t=0, the plane of the loop is perpendicular to the magnetic field B. If the number of turns of the loop be N then what is the instantaneous flux through the coil
  • BAN
  • BAN sin \omega t
  • BAN cos \omega t
  • BAN \omega t
A negative charged object attracts another charged object kept close to it. What is the nature of the charge on other object?
  • positive
  • negative
  • both
  • none
Two charges, each equal q, are kept at x=-a and x=a on the x-axis. A particle of mass m and charge {q_0} = \frac{q}{2} is placed at the origin. If  charge {q_0} is given a small displacement (y<<a) along the y-axis, the net force acting on the particle is proportional to: 
  • y
  • -y
  • \frac{1}{y}
  • -\frac{1}{y}
A negatively charged rod is held close to one side of a metal ball and the other side is earthed. Which of the following diagrams is correctly shows the charge distribution?
A positively charged glass rod is brought near the disc of uncharged gold leaf electroscope. The leaves diverge. Which of the following statements is correct?
  • No charge is present on the leaves
  • Positive charge is induced on the leaves
  • Negative charge is induced on the leaves
  • Positive charge is induced on the leave and negative charge on the other.
 When alternating current flows through a conductor, the rate of flux change 
  • Is higher in the inner part of the conductor
  • is lower in the inner part of the conductor
  • is uniform throughout the conductor
  • Depends on the resistivity of the conductor
A point charge q=10^{-11}\ C, is placed at 4\ cm above a square plate (8\ cm\ \times 8\ cm), having charge density 0.5\ \times 10^{-8}\ C/m^{2}. Find the flux related with it.
  • 0.188\ V-m
  • 0.12\ V-m
  • 0.288\ V-m
  • 0.388\ V-m
A charge q is distributed uniformly on a ring of radius R. A sphere of equal radius R is constructed with its centre at the periphery of the ring, Find the flux of the electric field through the surface of the sphere
1136650_b953e8c8eb8a4058b07d4a29fbd24855.png
  • \dfrac{q}{\epsilon_0}
  • \dfrac{q}{2\epsilon_0}
  • \dfrac{q}{3\epsilon_0}
  • Zero.
What is the electric flux linked with closed surface?
1134210_97be74d146c24ae9b08fb640e7996415.jpg
  • 10^{11} Nm^2/C
  • 10^{12} Nm^2/C
  • 10^{10} Nm^2/C
  • 8.85\times10^1{3} Nm^2/C
The electric field in a region of space is given by E=(5\ \hat {i}+2\hat {j})N/C. The electric flux through an area of 2\ m^{2} lying in the YZ plane, in S.I.. units is ?
  • 10
  • 20
  • 10\sqrt {2}
  • 2\sqrt {29}
The volume charge density as a function of distance x from one face inside a unit cube is varying as shown in the figure. Then the total flux (in S.I units) through the cube if (p-{0}=8085\times10^{-12}Cm^{3}) is
  • \dfrac{1}{4}
  • \dfrac{1}{2}
  • \dfrac{3}{4}
  • 1
A spherical shell of radius R has two holes A and B through which a ring having charge positive through without touching the shell. The flux through spherical shell is \dfrac{q}{3 \varepsilon_0}. Find the radius of the ring:-
1113137_7ab59f04651d40048533d99c70d6c438.png
  • R\sqrt{2}
  • 2 R
  • 0.5 R
  • R
If the electronic charge is 1.6\times 10^{-19}C, then the number of electrons passing through a section of wire per second, when the wire carries a current of 2 ampere is?
  • 1.25\times 10^{17}
  • 1.6\times 10^{17}
  • 1.25\times 10^{19}
  • 1.6\times 10^{19}
Four charge particle of charges -q,-q,-q and 3q are place at the vertices pf a square of side as shown.The magnitude of dipole moment of the arrangement is
1165731_284338915c894efe94fcded59c241a71.png
  • 2\sqrt 2 \;qa
  • qa
  • 3qa
  • \left( {2 + \sqrt 2 } \right)qa
Three point charges +q,\ -2q and +q, are passed at points (x=0,\ y=a,\ z=0),\ (x=0,\ y=0,\ z=0) and (x=a,\ y=0,\ z=0 ) respectively. The magnitude and direction of the electric dipole moment vector of this charge assembly are ?
  • \sqrt{2}\ qa along + x direction
  • \sqrt{2}\ qa along + y direction
  • \sqrt{2}\ qa along the line joining points (x=0,\ y=0,\ z=0) and (x=a,\ y=a,\ z=0)
  • qa along the line joining points (x=0,\ y=0,\ z=0) and (x=a,\ y=z,\ z=0)
Twelve infinite long wire of uniform linear charge density \left( \lambda  \right)  are passing along the twelve edges of a cube. Find electric flux through any face of cube 
1174997_c818de18256f43a696521b16c59a4f31.png
  • \left( \frac { \lambda l }{2 \varepsilon _{ { 0 } } } \right)
  • \left( \frac { \lambda l }{ \varepsilon _{ { 0 } } } \right)
  • \left( \frac { \lambda l }{3 \varepsilon _{ { 0 } } } \right)
  • \left( \frac { 3\lambda l }{ \varepsilon _{ { 0 } } } \right)
A conducting sphere of radius a has charge Q on it. It is enclosed by a neutral conducting concentric concentric spherical shell having inner radius 2a and outer radius 5a. Find electrostatic energy of system.
  • \dfrac{5}{12} \dfrac{kQ^2}{a}
  • \dfrac{11}{12} \dfrac{kQ^2}{a}
  • ]dfrac{kQ^2}{2a}
  • none
Charges q and q are given to the conducting shells in figure (i) and q and -q are given to the identical pair in figure (ii).
1138522_0d9db065c3854cfa8747842179452413.png
  • force of interaction between the shells in the figure (i) will be greater than that in figure (ii)
  • force of interaction between the shells in the figure (i) will be smaller than that in figure (ii)
  • force of interaction will be same in both the figures
  • nothing can be said
Figure shows electric field lines in which an electric dipole \rho is placed as shown. Which of the following statements is correct?
1138382_3a1f0e6824dc4ddbb88e07c3636566ba.png
  • The dipole will not experience any force
  • The dipole will not experience a force towards right
  • The dipole will not experience a force towards left
  • The dipole will not experience a force upwards
A non conducting sphere of radius 'a' has a type charge '+q' uniformly distributed throughout in volume. A hollow spherical conductor having inner and  outer, radii 'b' and 'c' and net charge '-q' is concentric with the sphere (see the figure)
Read the following statements
(i) The electric field at a distance r from the center of the sphere = \frac{1}{{4\pi {\varepsilon _0}}}\frac{{qr}}{{{a^3}}} for r<a.
(ii) The electric field at distance r from the center of the sphere for a<r<b=0
(iii) The electric field at distance r from the center of the sphere for b<r<c<=0
(iv) The charge on the inner surface of the hollow sphere =-q
(v) The charge on the outer surface of the hollow sphere =+q.
1137796_c4c98f5bc12743bc86ff67bc8052e5e6.PNG
  • (i),(ii) and (v)
  • (i),(iii) and (iv)
  • (ii),(iii) and (v)
  • (ii),(iii) and (iv)
An inductor having 400 turns, carrying of 8 m A and inductances 5 mH then flux is:
  • \mu_0
  • 4 \pi/\mu_0
  • \mu_0/4 \pi
  • 4 \pi
A point charge 50 \: \mu C is located in the XY plane at the point of position vector r_1 = 2i + 3j . What is the electric field at the point of position vector r_2 = 8i-5j.
  • 1200 v/m
  • 0.04 V/m
  • 900 V/m
  • 4500 V/m
The ratio of the forces between two charges placed at a certain distance apart in air and at half of the distance apart in medium of dielectric '2' is 
  • 1 : 4
  • 1 : 2
  • 4 : 1
  • 2 : 1

A point charge + 20\mu C is at a distance 4 cm above the center of a square of side 8 cm. What is the magnitude of electrostatic flux through the square?

  • 3.76 \times {15^5}{\text{N}}{{\text{m}}^2}{{\text{C}}^{ - 1}}
  • 4.2 \times {15^5}{\text{N}}{{\text{m}}^2}{{\text{C}}^{ - 1}}
  • 2.9 \times {15^5}{\text{N}}{{\text{m}}^2}{{\text{C}}^{ - 1}}
  • 5.1 \times {15^5}{\text{N}}{{\text{m}}^2}{{\text{C}}^{ - 1}}
Two charges q each attract each by a force of 100 N. Now, the entire space is filled with a medium of relative permittivity 10. The force exerted on any one of the charges by the medium is
  • 90 N
  • 10 N
  • 110 N
  • Zero
If the electric lines of force are as shown in figure. Electric field intensities at A and B are E_{A} and E_{B} respectively.
1187708_1824a6f2eee2420285324d225e82abe1.png
  • E_{A} < E_{B}
  • E_{A} > E_{B}
  • E_{A} = E_{B}
  • E_{A} = E_{B} = 0
A capacitor is a perfect insulator for:
  • constant direct current
  • alternating current
  • direct as well as alternating current
  • variable direct current.

What is the value of electric flux in SI unit in the Y-Z plane of area 2{m^2} , if intensity of electric field is \overrightarrow {\text{E}} {\text{ = }}\left( {{\text{5}}\widehat {\text{i}}{\text{ + 2}}\widehat {\text{j}}} \right){\text{N/C}}

  • 10
  • 20
  • 10\sqrt 2
  • 2\sqrt {29}

An electric dipole ( dipole moment p) is placed at a radial distance r>>a ( Where a is dipole length) from an infinite line of charge having linear charge density + \lambda . dipole moment vector is aligned along the radial vector \overrightarrow r force experienced by the dipole is:-

  • \dfrac{{\lambda p}}{{2\pi {\varepsilon _o}{r^2}}},{\text{attractive}}
  • \dfrac{{\lambda p}}{{2\pi {\varepsilon _o}{r^3}}},{\text{attractive}}
  • \dfrac{{\lambda p}}{{2\pi {\varepsilon _o}{r^2}}},{\text{repulsive}}
  • \dfrac{{\lambda p}}{{2\pi {\varepsilon _o}{r^3}}},{\text{repulsive}}
A cone of base radius R and height h is located in a uniform electric field {\vec E} parallel to its base. The electric flux entering the cone is 
  • EhR
  • \frac{1}{2}EhR
  • 4EhR
  • 2EhR
0:0:1


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