Physics Quiz Questions Answers Practice MCQS Test of Physics
1.The work function of lithium is 2.5 eV. The maximum wavelength of light that can cause the Photo-electric effect in lithium is.
A. 3980Å
B. 4980 Å
C. 5980 Å
D. 6980 Å
ANSWER: B
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2.The K.E of a photo-electron, emitted on shining a light of wavelength 6.2 x 10-6 m on a metal surface of work function 0.1 eV, is.
A. 0.01 eV
B. 0.02 eV
C. 0.1 eV
D. 1.0 eV
ANSWER: C
3.Photoelectrons stopping potential depends on.
A. Frequency of incident light and nature of cathode material
B. The intensity of incident light
C. The frequency of incident light
D. Nature of cathode material
ANSWER: A
4.The stopping potential value is 0.6 V when the light source is kept at a distance of 20 cm. When the same source is kept at 40 cm away, the stopping potential is.
A. 0.6 V
B. 0.3 V
C. 1.2 V
D. 2.4 V
ANSWER: A
5.The expression for the Compton shift is.
A.
B.
C.
D.
ANSWER: B
6.X-rays of wavelength 0.15 nm are scattered from a block of carbon. The wavelength of x-rays scattered at 0° is.
A. 0.15 nm
B. 0.154 nm
C. 0.165 nm
D. 0.178 nm
ANSWER: A
7.In Compton scattering, if the incident photon has a wavelength of 0.2 nm and ϕ = 90°, the angle at which recoil electron appears is.
A. 30.12°
B. 38.46°
C. 44.57°
D. 53.12°
ANSWER: C
8.When white light is passed through cool gases, the spectra observed is.
A. Line spectra
B. Continuous spectra
C. Emission line spectra
D. Absorption line spectra
ANSWER: D
9.X-rays of wavelength 100 pm are scattered from a carbon target at ϕ = 90°. The kinetic energy of the recoiling electron is.
A. 12.4 KeV
B. 12.4 J
C. 295 eV
D. 295 J
ANSWER: C
10.The de-Broglie wavelength, of an electron accelerated to a potential of 400 V, is.
A. 0.03 nm
B. 0.04 nm
C. 0.12 nm
D. 0.06 nm
ANSWER: D