CBSE Questions for Class 12 Medical Physics Atoms Quiz 6 - MCQExams.com

In a cathode ray tube, what is the effect on the beam of particles if the anode voltage is increased ?
  • Kinetic Energy of electron beam increase
  • Rate of  electron emission increase 
  • Kinetic energy of electron beam remains unchanged 
  • Rate of electron  emission decrease
In a cathode ray tube, what is the effect on the beam of particles if a hotter filament is used ?
  • Rate of electron emission remains unchanged
  • Rate of electron emission decreases
  • Rate of electron emission increases
  • Rate of electron emission increases then decreases 
State the approximate potential difference applied between the anode and filament cathode ray tube .
  • 1000 V
  • 50 V
  • 5 V
  • 1 V
How can the brightness of the pattern on the screen of cathode ray tube be changed?
  • Changing the target
  • By changing the current on grid
  • By changing the negative potential on grid
  • Can't be changed
Mark out the incorrect statement :
  • A free neutron can transform itself into photon
  • A free proton can transform itself into neutron
  • In beta minus decay, the electron originates from nucleus
  • All of the above
When $$\alpha$$-particle are sent through a thin metal foil, most of them go straight through the foil because:
  • $$\alpha$$-particles are much heavier than electrons
  • $$\alpha$$-particles are positively charged
  • most part of the atom is empty space
  • $$\alpha$$-particle move with high velocity
The Interaction energy between an electron and proton is very small when they are far apart.
  • True
  • False
The diagram below shows a cathode ray tube in which the arrow indicates a beam of charged particles approaching an electric field between the plates A and B. State the approximate potential difference applied between the anode and filament.
181252_39ad6c4a543a42a29d439fca52bf7bc4.png
  • 250 V
  • 500 V
  • 1000 V
  • None of the above
the anode is kept at positive potential with respect to the cathode.
  •  themions are get attracted towards the anode and accelerate towards the anode
  •  themions are get deviated  towards the anode and accelerate towards the anode
  •  themions get attracted towards the cathode  and accelerate towards the cathode 
  •  none of these
The diagram below shows a cathode ray tube in which the arrow indicates a beam of charged particles approaching an electric field between the plates A and B. State the amount of charge on each particle.

181236_b2c055c9569f422b9264af72f2c5deb1.png
  • $$1.6\, \times\, 10^{-19} C$$
  • $$-1.6\, \times\, 10^{-19} C$$
  • 0
  • $$-1.16\, \times\, 10^{-19} C$$
What are the one main components of a cathode ray tube ? 
  • electron gun
  • cathode tube
  • U-tube
  • none of these
The diagram below shows a cathode ray tube in which the arrow indicates a beam of charged particles approaching an electric field between the plates A and B. State the approximate voltage $$V_1$$ used to heat the filament.
181245_3cdd416e55a44b46b1c757617b363bc3.png
  • 1.5 V
  • 3 V
  • 6 V
  • 12 V
Diagram shows an electron gun inside a cathode ray tube. Which of the following is true?
181294_217fc7e9009f4a13b45dbddbbef776df.png
  • F is Filament, to heat the cathode X
  • X is Cathode, to emit the electrons
  • Y is Anode, to provide kinetic energy to electrons
  • All the above
In a cathode ray tube, the screen is coated with fluorescent material.
  • it produces spots on the screen 
  • beam of light is not in a straight line 
  • light deviates away after striking 
  • none of these 
The diagram below shows a cathode ray tube in which the arrow indicates a beam of charged particles approaching an electric field between the plates A and B. What will happen to the beam when it passes through the electric field?
181263_803ca524d8a748a09280a7de523261c0.png
  • Will pass undeflected
  • Will deflect towards B
  • Will have circular motion in between A and B
  • Will deflect towards A
In Bohr's model of the hydrogen atom, let $$R, V, T$$ and $$E$$ represent the radius of the orbit, speed of the electron, time period of revolution of electron and the total energy of the electron respectively. The quantity proportional to the quantum number n is
  • $$VR$$
  • $$E$$
  • $$r$$
  • $$T$$
The ratio of areas between the electron orbits for the first excited state to the ground state for the hydrogen atom is
  • $$2 : 1$$
  • $$4 : 1$$
  • $$8 : 1$$
  • $$16 : 1$$
Which of the following series in the spectrum of hydrogen atom lies in the visible region of the electromagnetic spectrum?
  • Paschen series
  • Balmer series
  • Lyman series
  • Brackett series
Hydrogen atom excites energy level from fundamental state to $$n=3$$. Number of spectral lines according to Bohr, is
  • $$4$$
  • $$3$$
  • $$1$$
  • $$2$$
Hydrogen atom excites energy level from fundamental state to $$n = 3$$. Number of spectral lines, according to Bohr, is
  • $$4$$
  • $$3$$
  • $$1$$
  • $$2$$
The approximate value of quantum number $$n$$ for the circular orbit of hydrogen $$0.0001 mm$$ diameter is
  • $$1000$$
  • $$60$$
  • $$10000$$
  • $$31$$
In an electron gun the control grid is given a negative potential relative to cathode in order to
  • Decelerate electrons
  • Repel electrons and thus to control the number of electrons passing through it
  • To select electrons of same velocity and to converge them along the axis
  • To decrease the kinetic energy of electrons
An element X has number of protons =What will be its mass number if it has 3 neutrons?
  • 4
  • 3
  • 7
  • 5
The energy levels of the hydrogen spectrum is shown in figure. There are some transitions $$A, B, C, D$$ and $$E$$. Transition $$A, B$$ and $$C$$ respectively represent

211136_219232df38f14540a5ef290ee483b05a.png
  • first member of Lyman series, third spectral line of Balmer series and the second spectral line of Paschen series
  • ionization potential of hydrogen, second spectral line of Balmer series, third spectral line of Paschen series
  • series limit of Lyman series, third spectral line of Balmer series and second spectral line of Paschen series
  • series limit of Lyman series, second spectral line of Balmer series and third spectral line of Paschen series
If in hydrogen atom, radius of $$n^{th}$$ Bohr orbits is $$r_n$$, frequency of revolution of electron in $$n^{th}$$ orbit is $$f_n$$, choose the correct option.
  • Both (a) and (b)
The specific charge for cathode rays is
  • Constant
  • Variable
  • Depend upon the material of the cathode
  • Depend upon the nature of the gas in the discharge tube
Alpha-particles that come closer to nuclei in Rutherford's alpha particle scattering experiment:
  • are deflected more
  • are deflected less
  • make more collisions
  • None of the above
In Rutherford's scattering experiment which of the following does not happen ?
  • Most of the $$\displaystyle \alpha $$-rays pass through without deflection
  • A few $$\displaystyle \alpha $$-particles pass through the nucleus
  • A few $$\displaystyle \alpha $$-particles are deflected back
  • $$\displaystyle \alpha $$-particles going near the nucleus are slightly deflected
The ratio ofthe radius of the orbit for the electron orbiting the hydrogen nucleus to that of an electron orbiting a deuterium nucleus is
  • 1:1
  • 1:2
  • 2:1
  • 1:3
Line spectrum is obtained from the :
  • Sun
  • Filament of the bulb
  • Mercury lamp
  • Burning coal
The radius of an atom is of the order of:
  • 10$$^{-10}$$ cm
  • 10$$^{-13}$$ cm
  • 10$$^{-15}$$ cm
  • 10$$^{-8}$$ cm
Beta particles are essentially:
  • neutrons
  • protons
  • electrons
  • helium nuclei
The Bohr's orbit radius for the hydrogen atom (n = 1) is approximately 0.53 A. The radius for the first excited state (n = 2) orbit is:
  • 0.27 A
  • 1.27 A
  • 2.12 A
  • 3.12 A
A piece of cloth looks red in sun light. If it is held in the blue portion of a solar spectrum, it will appear
  • Red
  • Black
  • Blue
  • White
If the radius of gold (Au) and platinum (Pt) atoms in pm is $$\displaystyle 100\sqrt{2}$$ and $$\displaystyle 90\sqrt{2}$$, respectively, find $$\displaystyle n_{Au}n_{Pt}$$.
  • $$0.52$$
  • $$0.68$$
  • $$0.73$$
  • $$0.74$$
To get line spectrum, the substances are excited in their
  • Solid state
  • Molecular state
  • Gaseous state
  • Atomic state
For the same kinetic energy, the momentum shall be maximum for
  • Electron
  • Proton
  • Deutron
  • Alpha particle
The radius of hydrogen atom in the first excited level is
  • twice
  • four times
  • same
  • half
The radius of a nucleus with mass number 16 is 3 fm. The radius of another nucleus with mass number 128 is
  • 6 fm
  • 12 fm
  • 18 fm
  • 24 fm
The spectrum of light emitted by an electric bulb is an example of
  • Emission spectrum
  • Absorption spectrum
  • Continuous spectrum
  • Line spectrum
Photons have the following characteristics:
(i) energy of a photon $$E=h\gamma$$
(ii) photons travel with the velocity of light
(iii) photons are emitted when light of frequency $$\gamma$$ is emitted by an atom
  • (i), (ii)
  • (ii), (iii)
  • (i), (ii) and (iii)
  • Only (i)
When light transmitted through the absorbing material after getting dispersed forms dark lines on a continuous bright background. This kind of spectrum formed is known as
  • Line spectrum
  • Band spectrum
  • Line absorption spectrum
  • Band absorption spectrum
The property of cathode rays used in the monitor of a computer is :
  • high velocity of the rays
  • high ionization power of the rays
  • the property to cause fluorescence
  • rectilinear propagation
In a vacuum diode, some of the electrons possessing sufficient kinetic energy can reach the plate even if the plate potential is negative. For a certain diode, the plate current becomes zero when plate potential is $$-10  V$$. What is the kinetic energy of the electrons in $$eV$$, if the plate potential is $$-4  V$$ ?
  • $$3 eV$$
  • $$6 eV$$
  • $$4 eV$$
  • $$-4 eV$$
In a CRT the acceleration of electrons is controlled by changing ________ between the cathode and anode.
  • potential difference
  • space
  • temperature
  • none of these
The particle used by Rutherford in $$\alpha$$-ray scattering experiment was__________.
  • neutron
  • electron
  • helium nuclei
  • X-rays
In a vacuum diode, $$2 \times {10}^{19}$$ electrons emitted from the cathode reach the plate of a vacuum diode in 4 seconds. Find the current and the power consumed if the potential difference between the cathode and the plate is $$200  V$$.
  • $$0.8 A, 160 W$$
  • $$0.8 A, 16 W$$
  • $$0.8 A, 1.6 W$$
  • $$0.8 A, 1600 W$$
The target used in a Coolidge tube for the production of X-rays is made up of ________ .
  • manganese
  • molybdenum
  • uranium
  • radium
The size of the nucleus is approximately:
  • $$10^{-18}$$ m
  • $$10^{-10}$$ m
  • $$10^{-8}$$ m
  • none of these
Gases exert pressure on the walls of the container, because the gas molecules
  • Have finite volume
  • Obey Boyle's law
  • Possess momentum
  • Collide with one another
0:0:1


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