NEET Physics Chapter Wise Mock Test – Photoelectric Effect

NEET Physics Chapter Wise Mock Test – Photoelectric Effect

Question 1:
Consider a beam of electrons (each electron with energy E₀) incident on a metal surface kept in an evacuated chamber. Then,
(a) no electrons will be emitted as only photons can emit electrons
(b) electrons can be emitted but all with an energy E₀
(c) electrons can be emitted with any energy, with a maximum of E₀-Φ(Φ is the work function)
(d) electrons can be emitted with any energy, with a maximum of E₀

Question 2:
The de-Broglie wavelength associated with an electron, accelerated through a potential difference of 100 V is
(a) 0.529 nm
(b) 52.9 nm
(c) 0.123 nm
(d) 1.23 nm

Question 3:
In an experiment photoelectrons are emitted when light of wavelength 4000Å is incident on it. They can be stopped by a retarding potential of 2V. if the wavelength of the incident light be 3000Å, the stopping potential will be
(a) 1V
(b) 1.5V
(c) 2V
(d) 3V

Question 4:

Question 5:
Photons absorbed in matter are converted to heat. A source emitting n photon/s of frequency ν is used to convert 1kg of ice at 0°C to water at 0°C. Then, the time T taken for the conversion
(a) increases with increasing n with ν fixed
(b) increases with n fixed ν increasing
(c) remains constant with n and ν changing such that, nν=constant
(d) increases when the product nν increases

Question 6:
Which of the following characteristics of photoelectric effect supports the particle nature of radiations?
(a) Threshold frequency
(b) Dependence of the velocity of photoelectron on frequency
(c) Independence of velocity of photoelectrons of intensity of radiations
(d) Instantaneous photoelectric emission

Question 7:
What is E in the Einstein’s photoelectric equation, E = hν – Φ₀, where ν is the frequency of incident radiations and Φ₀ is the work function?
(a) Kinetic energy of every photoelectron
(b) Mean kinetic energy of photoelectrons
(c) Minimum kinetic energy of photoelectrons
(d) Maximum kinetic energy of photoelectrons

Question 8:
A photocell employs photoelectric effect to convert
(a) change in the frequency of light into a change in electric voltage
(b) change in the intensity of illumination into a change in photoelectric current
(c) change in the intensity of illumination into a change in the work function of the photo cathode
(d) change in the frequency of light into a change in the electric current

Question 9:
From Einstein’s photoelectric equation, the graph of KE of the photoelectron emitted from the metal versus the frequency of the incident radiation gives a straight line graph, whose slope
(a) depends on the intensity of the incident radiation
(b) depends on the nature of the metal and also on the intensity of incident radiation
(c) is same for all metals and independent of the intensity of the incident radiation
(d) depends on the nature of the metal

Question 10:

Question 11:

Question 12:
When a piece of metal is illuminated by a monochromatic light of wavelength λ, then stopping potential is 3V_s.When same surface is illuminated by light of wavelength 2λ, then stopping potential becomes V_s. The value of threshold wavelength for photoelectric emission will be
(a) 4λ
(b) 8λ
(c) 4λ/3
(d) 6λ

Question 13:

Question 14:
Consider the following statements I and II are identify, the correct choice given in the answers.
I. In photovoltaic cells the photoelectric current produced is not proportional to the intensity of incident radiation.
II. In gas filled photoemissive cells, the velocity of photoelectrons depends on the wavelength of the incident radiation.
(a) Both statements are true
(b) Both statements are false
(c) I is true but II is false
(d) I is false but II is true

Question 15:
When a monochromatic point source of light is at a distance r from a photoelectric cell, the cut-off voltage is V and the saturation current is I. If the same source is placed at a distance 3r away from the photoelectric cell, then
(a) no change in saturation current and stopping potential
(b) saturation current will decrease and stopping potential will not change
(c) saturation current will increase and stopping potential will decrease
(d) None of the above

Question 16:
Ultraviolet beam of wavelength 280nm is incident on lithium surface of work function 2.5eV. The maximum velocity of electron emitted from metal surface is .
(a) 8.2×10⁵ m/s
(b) 10⁶ m/s
(c) 7×10⁵ m/s.
(d) 3.8×10⁶ m/s

Question 17:
In a photoelectric experiment it was found that the stopping potential decreases from 1.85V to 0.82V as the wavelength of incident light is varied from 300 nm to 400 nm. Planck constant from this data is
(a) 6.634 x 10^-34 eVs
(b) 4.12 x 10^-15 eVs
(c) 2 x 10^-30 eVs
(d) 6.63 x 10^-15 eVs

Question 18:
A horizontal cesium plate (Φ= 1.9 eV) is moved vertically downward at a constant speed v in a room full of radiation of wavelength 250 nm and above. The minimum value of v, so that the vertically upward component of velocity is non-positive for such a photoelectron.
(a) 1.04 x 10⁶ ms^-1
(b) 3 x 10⁴ ms^-1
(c) 2 x 10³ ms^-1
(d) None of these

Question 19:
A totally reflecting mirror placed horizontally faces a parallel beam of light as shown in figure. The mass of the mirror is 20g. Assume 30% of the light emitted by the source passes through the lens unabsorbed. The power of the source needed to support the mirror

(a) 10⁴ W
(b) 10² W
(c) 10⁸ W
(d) 10^-1 W

Question 20:
Ultraviolet light of wavelength 66.26 nm and intensity 2W/m² falls on potassium surface by which photoelectrons are ejected out. If only 0.1% of the incident photons produce’ photoelectrons, and surface area of metal surface is 4 m², then the number of electrons are emitted per second
(a) 2.67×10¹⁵
(b) 3×10¹⁵
(c) 3.33×10¹⁷
(d) 4.17×10¹⁶

Question 21:

Direction (Q.Nos. 22-26): In each of the following questions a statement of Assertion is given followed by a corresponding statement of Reason just below it. Of the statements mark the correct answer as
(a) If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
(b) If both Assertion and Reason are true but the Reason is not correct explanation of the Assertion
(c) If Assertion is true but Reason is false
(d) If both Assertion and Reason are false

Question 22:
Assertion (A): If the frequency of the light incident on a metal surface is doubled, the maximum kinetic energy of emitted photoelectron also gets doubled.
Reason (R): Kinetic energy of particle is proportional to frequency.

Question 23:
Assertion (A): The energy (E) and momentum (p) of photon are related by p=E/c.
Reason (R): The photon behaves like a particle.

Question 24:
Assertion (A): Photosensitivity of a metal is high, if its work function is small.
Reason (R): Work function=hf₀ where f₀ is the threshold frequency.

Question 25:
Assertion (A): Photoelectric effect demonstrates the wave nature of light.
Reason (R): The number of photoelectrons is proportional to the frequency of light.

Question 26:
Assertion (A): Photoelectric effect can take place only with an electron bound in the atom.
Reason (R): Electron is a fermion whereas proton is a boson.

Question 27:

Question 28:
If the kinetic energy of the particle is increased to 16 times its previous value, the percentage change in the de-Broglie wavelength of the particle is
(a) 25
(b) 75
(c) 60
(d) 50

Question 29:
When the energy of the incident radiation is increased by 20%, the kinetic energy of the photoelectrons emitted from a metal surface increased from 0.5 eV to 0.8 eV. The work function of the metal is
(a) 0.65 eV
(b) 1.0 eV
(c) 1.3 eV
(d) 1.5 eV

Question 30:
For photoelectric emission from certain metal the cut-off frequency is ν. If radiation of frequency 2ν impinges on the metal plate, the maximum possible velocity of the emitted electron will be (m is the electron mass)

Question 31:
The wavelength λ_e of an electron and λ_p of a photon of same energy E are related by

Question 32:
A light of wavelength 5000Å falls on a sensitive plate with photoelectric work function 1.90 eV. Kinetic energy of the emitted photoelectrons will be (Given, h = 6.62 x 10^-34 Js)
(a) 0.1 eV
(b) 2 eV
(c) 0.58 eV
(d) 1.581 eV

Question 33:
A 200W sodium street lamp emits yellow light of wavelength 0.6μm. Assuming it to be 25 % efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is
(a) 1.5×10²⁰
(b) 6×10¹⁸
(c) 62×10²⁰
(d) 3×10¹⁹

Question 34:
If a surface has a work function 4.0 eV, what is the maximum velocity of electrons liberated from the surface when it is irradiated with ultraviolet radiation of wavelength 0.2μm?
(a) 4.4 x 10⁵ m/s
(b) 8.8 x 10⁷ m/s
(c) 8.8 x 10⁵ m/s
(d) 4.4 x 10⁷ m/s

Question 35:
In photoelectric emission process from a metal of work function 1.8eV, the kinetic energy of most energetic electrons is 0.5eV. The corresponding stopping potential is
(a) 1.3 V
(b) 0.5 V
(c) 2.3 V
(d) 1.8 V

Question 36:
Light of two different frequencies whose photons have energies 1eV and 2.5 eV respectively illuminate a metallic surface whose work function is 0.5eV successively. Ratio of maximum speeds of emitted
(a) 1:2
(b) 1:1
(c) 1:5
(d) 1:4

Question 37:
Photoelectric emission occurs only when the incident light has more than a certain minimum
(a) wavelength
(b) intensity
(c) frequency
(d) power

Question 38:
The work functions for metals A, B and C are respectively 1.92 eV, 2.0 eV and 5 eV. According to Einstein’s equation, the metal (s) which will emit photoelectrons for a radiation of wavelength 4100Å is/are
(a) Only A
(b) A and B
(c) All of these
(d) None of these

Question 39:
In a photocell, with exciting wavelength lambda, the faster electron has speed v. If the exciting wavelength is changed to 3λ/4, the speed of the fastest electron will be

Question 40:
Photon and electron are given same energy (10-20 J). Wavelength associated with photon and electron are λ_p and λ_e, the correct statement will be
(a) λ_p>λ_e
(b) λ_p<λ_e
(c) λ_p=λ_e
(d) λ_e/λ_p=C

Question 41:
What will be the number of photons emitted per second by a 10W sodium vapour lamp assuming that 90% of the consumed energy is converted into light? [Wavelength of sodium light is 590 nm, and h = 6.63 x 10^-34 Js]
(a) 0.267 x 10¹⁸
(b) 0.267 x 10¹⁹
(c) 0.267 x 10²⁰
(d) 0.267 x 10¹⁷

Question 42:
Assertion(A): The threshold frequency of photoelectric effect supports the particle nature of sunlight.
Reason(R): If frequency of incident light is less than the threshold frequency, electrons are not emitted from metal surface.
(a) If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
(b) If both Assertion and Reason are true but the Reason is not correct explanation of the Assertion
(c) If Assertion is true but Reason is false
(d) If both Assertion and Reason are false

Answers:

Hints And Solutions:

PhysicsChemistryBiology