Quantum Physics Quiz | objective questions | Physics General Knowledge Questions | MCQ

Quantum Physics Quiz | objective questions | Physics General Knowledge Questions | MCQ

1 >>work function of a metal is the ?

• (A) energy required by an electron to get absorbed in the metal surface
• (B) energy required by an electron to escape from the metal surface
• (C) minimum energy required by an electron to escape from the metal surface
• (D) maximum energy required by an electron to escape from the metal surface

Solution Work function of a metal is the minimum energy required by an electron to escape from the metal surface

2 >>In which case is electron emission from a metal not known? ?

• (A) Illuminating a metal surface with suitable light
• (B) Heating the metal sufficiently
• (C) Applying a very strong magnetic field to a metal
• (D) Applying a very strong electric field to a metal

Solution Applying a very strong magnetic field to a metal we didn't know the electron emission

3 >>Photoelectric effect is ?

• (A) emission of electrons by glass when illuminated by light of suitable frequency
• (B) emission of electrons by metals when heated
• (C) emission of electrons by insulators when illuminated by light of suitable frequency
• (D) emission of electrons by metals when illuminated by light of suitable frequency

Solution The photoelectric effect or photoemission is the production of electrons or other free carriers when light is shone onto a material. Electrons emitted in this manner can be called photoelectrons.

4 >>Photoelectric effect is possible ?

• (A) with only visible
• (B) with only ultraviolet
• (C) with both visible and uv depending on the metal
• (D) with only white light

Solution The photoelectric effect or photoemission is the production of electrons or other free carriers when light is shone onto a material. Electrons emitted in this manner can be called photoelectrons.

5 >>In Photoelectric effect ?

• (A) light is converted into electrical energy
• (B) electrical energy is converted into heat
• (C) electrical energy is converted magnetic field energy
• (D) electrical energy is converted into light energy

Solution The photoelectric effect or photoemission is the production of electrons or other free carriers when light is shone onto a material. Electrons emitted in this manner can be called photoelectrons.

6 >>n the experimental set up for studying photoelectric effect, if keeping the frequency of the incident radiation and the accelerating potential fixed, the intensity of light is varied, then ?

• (A) photocurrent decreases nonlinearly with intensity
• (B) photocurrent remains same with intensity
• (C) photocurrent decreases linearly with intensity
• (D) photocurrent increases linearly with intensity

Solution n the experimental set up for studying photoelectric effect, if keeping the frequency of the incident radiation and the accelerating potential fixed, the intensity of light is varied, then photocurrent increases linearly with intensity

7 >>Stopping potential in the experimental set up ?

• (A) negative potential V0 given to the plate A for which the photocurrent stops or becomes zero
• (B) positive potential V0 given to the plate A for which the photocurrent saturates
• (C) positive potential V0 given to the plate A for which the photocurrent stops or becomes zero
• (D) positive potential V0 given to the plate A for which the photocurrent stops increasing

Solution Stopping potential in the experimental set up negative potential V0 given to the plate A for which the photocurrent stops or becomes zero

8 >>For a given frequency of light and a positive plate potential in the set up , If the intensity of light is increased then ?

• (A) current is inversely proportional to intensity
• (B) current is unaffected by more intensity
• (C) current is more with more intensity
• (D) current is less with more intensity

Solution For a given frequency of light and a positive plate potential in the set up , If the intensity of light is increased then current is more with more intensity

9 >>In various experiments on photo electricity the stopping potential for a given frequency of the incident radiation ?

• (A) is proportional to radiation intensity
• (B) is independent of the radiation intensity
• (C) is independent of radiation intensity
• (D) is inversely proportional to radiation intensity

Solution In various experiments on photo electricity the stopping potential for a given frequency of the incident radiation is independent of radiation intensity

10 >>In various experiments on photo electricity dealing with the stopping potential dependence on frequency of incident radiation , the conclusion was that stopping potential ?

• (A) depends on the light intensity
• (B) is independent of frequency
• (C) depends on the frequency
• (D) depends on the initial current

Solution In various experiments on photo electricity dealing with the stopping potential dependence on frequency of incident radiation , the conclusion was that stopping potential depends on the frequency

11 >>According to the Einstein’s model minimum energy needed for the electron to escape from a metal surface having work function ϕ₀, the electron is emitted with maximum kinetic energy Kmax = ?

• (A) hν - ϕ₀
• (B) hν
• (C) hν + ϕ₀
• (D) hν - 2 ϕ₀

Solution According to the Einstein’s model minimum energy needed for the electron to escape from a metal surface having work function ϕ0, the electron is emitted with maximum kinetic energy Kmax = hν - ϕ0

12 >>According to the Einstein’s model the threshold frequency for a metal having work function ϕ₀ is given by ?

• (A) ϕ₀h +100
• (B) h/∅₀
• (C) ∅₀/h
• (D) ϕ₀h

Solution According to the Einstein’s model the threshold frequency for a metal having work function ϕ0 is given by ∅0/h

13 >>In interaction of radiation with matter, radiation behaves as if it is made up of particles called ?

• (A) electron
• (B) proton
• (C) bosons
• (D) positron

Solution A proton is a subatomic particle, symbol p or p+, with a positive electric charge of +1e elementary charge and mass slightly less than that of a neutron. Protons and neutrons, each with masses of approximately one atomic mass unit, are collectively referred to as nucleons.

14 >>Each photon has the same speed but different ?

• (A) rest mass
• (B) radius
• (C) frequency
• (D) energy

Solution Each photon has the same speed but different frequency

15 >>Mirage is due to ?

• (A) unequal heating of different parts of the atmosphere
• (B) magnetic disturbances in the atmosphere
• (C) depletion of ozone layer in the atmosphere
• (D) equal heating of different parts of the atmosphere

Solution The Above Phenomenon is a great example of TOTAL INTERNAL REFLACTION, Which comes in account when light travels from denser medium to rearer medium, after some specific angle it again reflacts into the denser medium. Similar kind of activity happens in desert area called Mirage or Marichica.

16 >>Photon has a charge of ?

• (A) 0
• (B) +2e; e= charge on electron
• (C) -e; e= charge on electron
• (D) -2e; e= charge on electron

Solution A proton is a subatomic particle, symbol p or p+, with a positive electric charge of +1e elementary charge and mass slightly less than that of a neutron. Protons and neutrons, each with masses of approximately one atomic mass unit, are collectively referred to as nucleons.

17 >>Photons can be ?

• (A) deflected by magnetic fields
• (B) scattered
• (C) deflected by magnetic fields
• (D) deflected by electric fields

Solution A proton is a subatomic particle, symbol p or p+, with a positive electric charge of +1e elementary charge and mass slightly less than that of a neutron. Protons and neutrons, each with masses of approximately one atomic mass unit, are collectively referred to as nucleons.

18 >>In a photon-particle collision (such as photon-electron collision) the quantity which is not conserved is ?

• (A) number of photons
• (B) total energy
• (C) None of the above
• (D) total momentum

Solution In a photon-particle collision (such as photon-electron collision) the quantity which is not conserved is number of photons

19 >>De Broglie proposed that the wave length λ associated with a particle of momentum p = mv is given as ?

• (A) h/2mv
• (B) mv/h
• (C) 2h/mv
• (D) h/mv

Solution The de Broglie wavelength is the wavelength, λ, associated with a massive particle and is related to its momentum, p, through the Planck constant, h: λ = h p .

20 >>Davisson Germer experiment proves that ?

• (A) electrons exhibit particle nature
• (B) protons exhibit wave nature
• (C) neutrons exhibit wave nature
• (D) electrons exhibit wave nature

Solution Davisson Germer experiment proves that electrons exhibit wave nature

21 >>A photon is ?

• (A) a quantum of light energy
• (B) a quantum of matter
• (C) an instrument for measuring light intensity
• (D) a positive charged particle

Solution A photon is an elementary particle, the quantum of all forms of electromagnetic radiation including light. It is the force carrier for electromagnetic force, even when static via virtual photons.

22 >>A photoelectric cell converts ?

• (A) light energy into electric energy
• (B) electric into light energy
• (C) light energy into heat energy
• (D) light energy into sound energy

Solution a device using a photoelectric effect to generate current.

23 >>The momentum of photon having energy E is ?

• (A) E/h
• (B) 0
• (C) E/c²
• (D) E/c

Solution The momentum of photon having energy E is E/c

24 >>Photo-electric effect can be explained only by assuming that light ?

• (A) is a form of longitudinal waves
• (B) consists of quanta
• (C) can be polarized
• (D) is a form of transverse waves

Solution The photoelectric effect or photoemission is the production of electrons or other free carriers when light is shone onto a material. Electrons emitted in this manner can be called photoelectrons.

25 >>The energy of a photon corresponding to the visible light of maximum wavelength is approximately ?

• (A) 3.2 eV
• (B) 1.6 ev
• (C) 1 eV
• (D) 7 eV

Solution The energy of a photon corresponding to the visible light of maximum wavelength is approximately 3.2 eV

26 >>In order to increase the kinetic energy of ejected photoelectrons, there should be an increase in ?

• (A) intensity of radiation
• (B) Both the wavelength and intensity of radiation
• (C) wavelength of radiation
• (D) frequency of radiation

Solution In order to increase the kinetic energy of ejected photoelectrons, there should be an increase in frequency of radiation

27 >>If h is Planck’s constant, the momentum of a photon of wavelength 0.01 A⁰ is ?

(A) 1012h

(B) h
(C) 102h
(D) 1012h
Solution The de Broglie wavelength is the wavelength, λ, associated with a massive particle and is related to its momentum, p, through the Planck constant, h: λ = h p .28 >>Planck’s constant has the dimensions of ?

• (A) energy
• (B) angular momentum
• (C) forcr
• (D) linear momentum

Solution a fundamental constant, equal to the energy of a quantum of electromagnetic radiation divided by its frequency, with a value of 6.626 × 10−34 joules.

29 >>Number of ejected photoelectrons increases with increase ?

• (A) in frequency of light
• (B) in intensity of light
• (C) never
• (D) in wavelength of light

Solution Number of ejected photoelectrons increases with increase in intensity of light

30 >>A photon behaves as if it had a mass equal to ?

• (A) hv/c
• (B) c²/hv
• (C) hv/c²
• (D) hvc

Solution A photon behaves as if it had a mass equal to hv/c2

31 >>If the energy of a photon corresponding to a wave length of 6000 A⁰ is 3.32 ×10¹⁹ joule, the photon energy for a wavelength of 4000 A⁰

• (A) 2.22 ×10¹⁹ joules
• (B) 5.98×10¹⁹ joules
• (C) 6.98×10¹⁹ joules
• (D) 4.98×10¹⁹ joules

Solution Use E =hc/(/lambda)

32 >>The work function for aluminium surface is 4.2 eV. The cutoff wavelength for the photo electric effect for the surface is ?

• (A) 3100 A⁰
• (B) 2400 A⁰
• (C) 1500 A⁰
• (D) 2955 A⁰

Solution use W=hVo

33 >>The work function of a photoelectric material is 3.32 eV. The threshold frequency will be equal to ?

• (A) 9 ×10¹⁴ HZ
• (B) 6 ×10¹⁴ HZ
• (C) 8 ×10¹⁴ HZ
• (D) 7 ×10¹⁴ HZ

Solution use W=hVo

34 >>Light of wavelength 4000 A⁰ is incident on a metal plate whose work function is 2 eV. The maximum kinetic energy of the emitted photoelectrons would be ?

• (A) 0.5eV
• (B) 1.5 eV
• (C) 1.1eV
• (D) 2.0eV

Solution use W=hVo and E = hc/(/lambda)

35 >>Given h = 6.6 ×10⁻³⁴ joule sec, the momentum of each photon in a given radiation is 3.3 ×10⁻²⁹ kg metre/sec. The frequency of radiation is ?

• (A) 1.7 ×10¹³ Hz
• (B) 1.8 ×10¹³ Hz
• (C) 1.5 ×10¹³ Hz
• (D) 1.6 ×10¹³ Hz

Solution use de brogli formula

36 >>If 10⁹ electrons move out of a body to another body every second, how much time is approximately required to get a total charge of 1 C on the other body? ?

• (A) 180 years
• (B) 220 years
• (C) 200 years
• (D) 120 years

Solution Total charge transferred per second q=ne=109×1.6×10-19=1.6×10-10C. So 1.6×10-10C charge transferred in time=1second

37 >>If the wavelength of light falling on a surface is increased from 3000 A⁰ to 3040 A⁰, then what will be the corresponding change in the stopping potential (given that hc = 12.4×10⁷ eVÅ)? ?

• (A) (-7.5) ×10⁻¹² V
• (B) (-8.5) ×10⁻¹²V
• (C) ( -5.5) ×10⁻¹² V
• (D) (-6.5) ×10⁻¹² V

Solution use W=hVo and E = hc/(/lambda)

38 >>If the wavelength of light incident on photo-electric cell be reduced from 4000A⁰ to3600A⁰,then what will be the change in the cut off potential. ?

• (A) 0.42Volt
• (B) 0.43Volt
• (C) 0.34Volt
• (D) 0.30Volt

Solution use W=hVo and E = hc/(/lambda)

39 >>If the voltage across the electrodes of a cathode ray tube is 500 volts then energy gained by the electrons is ?

• (A) 7 ×10⁻¹⁷ J
• (B) 9 ×10⁻¹⁷ J
• (C) 8 ×10⁻¹⁷ J
• (D) 6 ×10⁻¹⁷ J

Solution Use E=eV

40 >>Which of the following is correct about photoelectric cell? ?

• (A) converts light energy into heat energy
• (B) converts electric into light energy
• (C) converts light energy into sound energy
• (D) converts light energy into electric energy

Solution a device using a photoelectric effect to generate current.

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