The work function of a substance is 4.0 eV. The longest wavelength of light that can cause photoelectron emission from this substance is approximately

(a) 540 nm                  (b) 400 nm
(c) 310 nm                  (d) 220 nm

Concept Questions :-

Electron emission
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

The maximum kinetic energy of photoelectrons emitted from a surface when photons of energy 6 eV fall on it is 4 eV. The stopping potential in volts is

(a) 2                      (b) 4
(c) 6                      (d) 10

Concept Questions :-

Electron emission
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

Work function of a metal is 2.1 eV. Which of the waves of the following wavelengths will be able to emit photoelectrons from its surface ?
(a) 4000 Å, 7500 Å                      (b) 5500 Å, 6000 Å
(c) 4000 Å, 6000 Å                      (d) None of these

Concept Questions :-

Electron emission
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

The cathode of a photoelectric cell is changed such that the work function changes from ${\mathrm{W}}_{1}$ to ${\mathrm{W}}_{2}$ $\left({\mathrm{W}}_{2}>{\mathrm{W}}_{1}\right)$. If the current before and after the change are ${\mathrm{I}}_{1}$ and ${\mathrm{I}}_{2}$, all other conditions remaining unchanged, then (assuming $\mathrm{h\nu }>{\mathrm{W}}_{2}$) :

(a) ${\mathrm{I}}_{1}$= ${\mathrm{I}}_{2}$               (b) ${\mathrm{I}}_{1}$${\mathrm{I}}_{2}$
(c) ${\mathrm{I}}_{1}$>${\mathrm{I}}_{2}$                (d) ${\mathrm{I}}_{1}<{\mathrm{I}}_{2}<2{\mathrm{I}}_{1}$

Concept Questions :-

Electron emission
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

A beam of light of wavelength $\mathrm{\lambda }$ and with illumination L falls on a clean surface of sodium. If N photoelectrons are emitted each with kinetic energy E, then
(a) N ∝ L and E ∝ L                    (b) N ∝ L and $\mathrm{E}\propto \frac{1}{\mathrm{\lambda }}$
(c) $\mathrm{N}\propto \mathrm{\lambda }$ and E ∝ L                    (d) $\mathrm{N}\propto \frac{1}{\mathrm{\lambda }}$ and $\mathrm{E}\propto \frac{1}{\mathrm{L}}$

Concept Questions :-

Electron emission
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

Which of the following statements is correct

(a) The current in a photocell increases with increasing frequency of light

(b) The photocurrent is proportional to applied voltage

(c) The photocurrent increases with increasing intensity of light

(d) The stopping potential increases with increasing intensity of incident light

Concept Questions :-

Photoelectric effect experiment
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

For intensity I of a light of wavelength 5000Å the photoelectron saturation current is 0.40 $\mathrm{\mu A}$and stopping potential is 1.36 V, the work function of metal is

(a) 2.47 eV               (b) 1.36 eV
(c) 1.10 eV               (d) 0.43 eV

Concept Questions :-

Einstein photo-electric equation
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

The work functions of metals A and B are in the ratio 1 : 2. If light of frequencies f and 2f are incident on the surfaces of A and B respectively, the ratio of the maximum kinetic energies of photoelectrons emitted is (f is greater than threshold frequency of A, 2f is greater than threshold frequency of B)
(a) 1 : 1               (b) 1 : 2
(c) 1 : 3               (d) 1 : 4

Concept Questions :-

Einstein photo-electric equation
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

Light of frequency v is incident on a substance of threshold frequency ${\mathrm{v}}_{0}\left({\mathrm{v}}_{0}<\mathrm{v}\right)$. The energy of the emitted photo-electron will be
(a) $\mathrm{h}\left(\mathrm{v}-{\mathrm{v}}_{0}\right)$                  (b) h/v
(c) $\mathrm{he}\left(\mathrm{v}-{\mathrm{v}}_{0}\right)$                (d) $\mathrm{h}/{\mathrm{v}}_{0}$

Concept Questions :-

Electron emission
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

4 eV is the energy of the incident photon and the work function in 2eV. What is the stopping potential ?

(a) 2V                    (b) 4V
(c) 6V                    (d)

Concept Questions :-

Photoelectric effect experiment