Topic Modern Physics - Nuclie, Class 12 Physics MCQ Quiz Test

MCQ 1:
Two different photons of energies, 1 eV and 2.5 eV, fall on two identical metal plates having work function 0.5 eV, Then the ratio of maximum KE of the electrons emitted from the two surface is-

1 : 2
1 : 4
2 : 1
4 : 1

MCQ 2:
Ultraviolet light of wavelength 280 nm is used in an experiment on photo electric effect with lithium (φ = 2.5 eV) cathode. Stopping potential will be-

1 .9 eV
1.9 V
4.4 eV
4.4 V

MCQ 3:
A monochromatic source of light operating at 200 W emits 4 × 10²⁰ photons per second. Find the wavelength of light.

400 mm
200 n
4 × 10^–10 Å
None

MCQ 4:
Which metal will be suitable for a photo electric cell using light of wavelength 4000Å. The work functions of sodium and copper are respectively 2.0 eV and 4.0 eV.

sodium
copper
Both
None of both

MCQ 5:
The work function for the surface of aluminum is 4.2 eV. What will be the wavelength of that incident light for which the stopping potential will be zero.

2496 Å
2946 × 10^–7 m
2649 Å
2946 Å

MCQ 6:
Slope of V₀ – ν curve is -

e
h/e
φ₀
h

MCQ 7:
A radio station is transmitting waves of wavelength 300 m, If diffracting power of transmitter is 10 kw, then numbers of photons diffracted per second is-

1.5 × 10³⁵
1.5 × 10³¹
1.5 × 10²⁹
1.5 × 10³³

MCQ 8:
Light of wavelength 332 Å incidents on metal surface (work function = 1.07 eV). To stop emission of photo electron, retarding potential required to be-

3.74 V
2.67 V
1.07 V
4.81 V

MCQ 9:
Light of wavelength 5000 Å falls on a sensitive surface. If the surface has received 10^–7 Joule of energy, then what is the number of photons falling on the surface ?

25 × 10¹¹
25 × 10¹²
0.25 × 10¹¹
2.5 × 10¹¹

MCQ 10:
An electromagnetic radiation of frequency 3 × 10¹⁵ cycles per second falls on a photo electric surface whose work function is 4.0 eV. Find out the maximum velocity of the photo electrons emitted by the surface-

13.4 × 10^–19 m/s
19.8 × 10^–19 m/s
1.73 × 10⁶ m/s
None of these

MCQ 11:
The wavelength of a photon is 4000 Å. Calculate its energy.

49.5 × 10^–19 J
495 × 10^–19 J
4.95 × 10^–19 K
4.95 × 10^–19 J

MCQ 12:
When ultraviolet light of energy 6.2 eV incidents on a aluminimum surface, it emits photo electrons. If work function for aluminium surface is 4.2 eV, then kinetic energy of emitted electrons is-

3.2 × 10^–19 J
3.2 × 10^–17 J
3.2 × 10^–16 J
3.2 × 10^–11 J

MCQ 13:
Using light of wavelength 6000 Å stopping potential is obtained 2.4 volt for photo electric cell. If light of wavelength 4000 Å is used then stopping potential would be-

2.9 V
1.9 V
3.43 V
9.4 V

MCQ 14:
When light source is placed at 1 m distant from photo electric cell, then value of stopping potential is obtained 4 volt. If it is placed at 4 m distant, then value of stopping potential becomes -

2 volt
1 volt
4 volt
16 volt

MCQ 15:
When monochromatic light of wavelength &lamda; illuminates a metal surface then stopping potential for photo electric current is 3V₀. If wavelength changes to 2λ then stopping potential becomes V₀ . Threshold wavelength for photo electric emission is-

4 λ
8 λ
4/3 λ
6 λ

MCQ 16:
The graph between the energy of photoelectrons (E) and the wavelength of incident light (λ) is -

MCQ 17:
For a photoelectric cell, the graph showing the variation of cut off voltage (V₀) with frequency (ν) of incident light is -

(i)
(ii)
(iii)
(iv)

MCQ 18:
The K.E. of the photoelectrons is E when the incident wavelength is &lamda;/2. The K.E. becomes 2E when the incident wavelength is &lamda;/3. The work function of the metal is -

hc/λ
2hc/λ
3hc/λ
hc/3λ

MCQ 19:
One electron & one proton is accelerated by equal potential. Ratio in their de-broglie wavelength is

√(m_p/m_e)
m_e/m_p
m_p/m_e
1

MCQ 20:
De-broglie wavelength of a electron is 10 Å then velocity will be -

7.2 × 10⁷ m/s
7.2 × 10⁶ m/s
7.2 × 10⁵ m/s
7.2 × 10⁴ m/s

MCQ 21:
One electron & one proton have equal energies then ratio of associated de-broglie wavelength will be -

1 : (1836)²
√1836 : 1
1836 : 1
(1836)² : 1

MCQ 22:
Ratio of wavelength of duetron & proton accelerated by equal potential-

1/√2
√2
1/2
2

MCQ 23:
Energy of a α-particle, having debroglie wavelength of 0.004 Å.

1275 eV
1200 KeV
1200 MeV
1200 GeV

MCQ 24:
Velocity of a proton is c/20. Associated de-broglie wavelength is -

2.64 × 10^–24 mm
2.64 × 10^–24 cm
2.64 × 10^–14 Å
2.64 × 10^–14 m

MCQ 25:
Associated de-broglie wavelength of a electron in n^th bohr's orbit is -

2πr/n Å
2πn Å
1/n Å
nλ Å

MCQ 26:
De-broglie wavelength of a rotating electron around a nucleus of hydrogen atom at the fundamental energy level is-

0.3 Å
3.3 Å
6.62 Å
10 Å

MCQ 27:
From rest a electron is accelerated between two such points which has potential 20 & 40 volts respectively. Associated Debroglie wavelength of electron is -

0.75 Å
7.5 Å
2.75 Å
2.75 m

MCQ 28:
An electron microscope uses 40 KeV electrons. Find its resolving limit on the assumption that it is equal to the wavelength of the electron -

0.61 Å
0.6 Å
0.06 Å
0.061 Å

MCQ 29:
A hydrogen atom moving at a speed v absorbs a photon of wavelength 122 nm and stops. Find the value of v. (mass of hydrogen atom = 1.67 × 10^–27 kg)

3.5 m/s
32.5 m/s
3.05 m/s
3.25 m/s

MCQ 30:
The de-broglie wavelength of an electron is 0.2 Å. Calculate the potential difference required to retard it to rest -

3.76 × 10^–3 V
3.76 × 10³ V
3.76 × 10³ eV
376.5 V

MCQ 31:
An α-particle and a singly ionized ₄Be⁸ atom are accelerated through the same potential difference. Ratio of de-broglie wavelength-

1 : 2
2 : 1
4 : 1
1 : 1

MCQ 32:
The de-broglie wavelength of the electron in the second Bohr orbit is (given the radius of the first orbit r₁ = 0.53 Å)

3.33 Å
6.66 Å
9.99 Å
1.06 Å

MCQ 33:
The de-Broglie wavelength associated with an electron having a kinetic energy of 10 eV is

10 Å
12.27 Å
3.9 Å
0.10 Å