# Stopping Potential Revisited

## Trending Questions

**Q.**The work function of metal is 1 eV. Light of wavelength 3000 Å is incident on this metal surface. The velocity of emitted photo-electrons will be

- 1×106 m/sec
10 m/sec

1×103 m/sec

- 1×104 m/sec

**Q.**A metal surface of work function 1.07 eV is irradiated with light of wavelength 332 nm. The retarding potential required to stop the escape of photoelectrons is

4.81 eV

3.74 eV

- 1.07 eV
- 2.66 eV

**Q.**

In a photoelectric effect experiment, the graph of stopping potential V versus reciprocal of wavelength obtained is shown in the figure. As the intensity of incident radiation is increased:

Straight line shifts to right

Straight line shifts to left

Slope of the straight line get more steep

Graph does not change

**Q.**

The maximum wavelength of radiation that can produce photoelectric effect in a certain metal is 200 nm. The maximum kinetic energy acquired by electron due to radiation of wavelength 100 nm will be

6.2 eV

12.4 eV

100 eV

200 eV

**Q.**

Sodium and copper have work functions 2.3eV and 4.5eVrespectively. Then the ratio of their threshold wavelengths is nearest to

1 : 2

4 : 1

2 : 1

1 : 4

**Q.**In a photoelectric experiment for 4000 Å incident radiation, the potential difference to stop the ejection is 2 V. If the incident light is changed to 3000 Å, then the potential required to stop the ejection of electrons will be

- 2 V
- Less than 2 V
- Zero
- Greater than 2 V

**Q.**The light of two different frequencies whose photons have energies 3.8 eV and 1.4 eV respectively, illuminate a metallic surface whose work function is 0.6 eV successively. The ratio of maximum speeds of emitted electrons for the two frequencies respectively will be

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

**Q.**Light of wavelength 4000 Å is incident on a sodium surface for which the threshold wave length of photo – electrons is 5420 Å. The work function of sodium is

- 0.57 eV
2.29 eV

1.14 eV

4.58 eV

**Q.**Threshold wavelength for photoelectric effect on sodium is 5000 Å. Its work function is

- 15 J
- 16×10−14J
- 4×10−81J
- 4×10−19J

**Q.**

Light of wavelength λ strikes a photo-sensitive surface and electrons are ejected with kinetic energy E. If the kinetic energy is to be increased to 2E, the wavelength must be changed to λ′ where

λ′=2λ

λ2<λ′<λ

λ′=λ2

λ′>λ

**Q.**

Light incident normally on a plane mirror attached to a galvanometer coil retraces backwards as shown in Fig. 9.36. A current in the coil produces a deflection of 3.5° of the mirror. What is the displacement of the reflected spot of light on a screen placed 1.5 m away?

**Q.**

The
energy flux of sunlight reaching the surface of the earth is 1.388 ×
10^{3}
W/m^{2}.
How many photons (nearly) per square metre are incident on the Earth
per second? Assume that the photons in the sunlight have an average
wavelength of 550 nm.

**Q.**The surface of certain metal is first illuminated with light of wavelength λ1=350 nm and then, by light of wavelength λ2=540 nm. It is found that the maximum speed of the photo electrons in the two cases differ by a factor of 2. The work function of the metal (in eV) is close to:

(Energy of photon=1240λ(in nm)eV)

- 5.6
- 1.8
- 2.5
- 1.4

**Q.**

If the energy of a photon corresponding to a wavelength of 6000∘A is 3.32×10−19J, the photon energy for a wavelength of 4000∘A will be

1.4 eV

4.9 eV

3.1 eV

1.6 eV

**Q.**

The work functions of metals A and B are in the ratio 1 : 2. If light of frequencies fand 2fare 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)

1 : 3

1 : 1

1 : 2

1 : 4

**Q.**

Two identical metal plates show photoelectric effect by a light of wavelength λA falls on plate A and λB on plate B (λA=2λB). The maximum kinetic energy is

2KA=KB

KA<KB2

KA=2KB

KA=KB2

**Q.**

Light of wavelength 5000 ∘A falls on a sensitive plate with photoelectric work function of 1.9 eV. The kinetic energy of the photoelectron emitted will be

0.58 eV

2.48 eV

1.24 eV

1.16 eV

**Q.**

A monochromatic light source of intensity 5 mW emits 8 ×1015 photons per second. This light ejects photo electrons from a metal surface. The stopping potential for this setup is 2.0 V. Calculate the work function of the metal.

**Q.**If m is the mass of an electron and c is the speed of light, the ratio of the wavelength of a photon of energy E to that of the electron of the same energy is,

- c√2mE
- √2mE
- √2mcE
- √mE

**Q.**A source of 30W illuminates the cathode of a photocell with radiation of wavelength 6600angrastom.The saturation current will be (efficiency of photoelectric emission is 1%)

**Q.**The photoelectric threshold wavelength for a metal surface is 6600∘A . The work function for this is

- 1.87 V
- 0.18 eV
- 18.7 eV
- 1.87 eV

**Q.**

The photoelectric work function for a metal surface is 4.125 eV. The cut-off wavelength for this surface is

4125 ∘A

2062.5 ∘A

3000 ∘A

6000 ∘A

**Q.**

In a p-n junction, the depletion region is 400 nm wide and an electric field of 5×105 V m−1 exists in it. (a) Find the height of the potential barrier. (b) What should be the minimum kinetic energy of a conduction electron which can diffuse from the n-side to the p-side ?

**Q.**

In photoelectric effect stopping potential is $3{V}_{0}$ for incident wavelength ${\lambda}_{0}$ and stopping potential for incident wavelength$2{\lambda}_{0}$. Find threshold wavelength.

$3{\lambda}_{0}$

$2{\lambda}_{0}$

$4{\lambda}_{0}$

$8\lambda $

**Q.**

Light of wavelength 1824 ∘A, incident on the surface of a metal, produces photo-electrons with maximum energy 5.3 eV. When light of wavelength 1216 ∘A is used, the maximum energy of photoelectrons is 8.7 eV. The work function of the metal surface is

13.6 eV

6.8 eV

3.5 eV

1.5 eV

**Q.**

Stopping potential for photoelectrons

Depends on both the frequency of the incident light and nature of the cathode material

- Depends upon the intensity of the incident light
Does not depend on the frequency of the incident light

Does not depend upon the nature of the cathode material

**Q.**

How many photons are emitted by a laser source $5\times {10}^{-3}W$ operating at $632.2nm$ in $2s$?

$3.2\times {10}^{16}$

$1.6\times {10}^{16}$

$4\times {10}^{16}$

None of these

**Q.**When radiation is incident on a photoelectron emitter, the stopping potential is found to be 9 volts. If e/m for the electron is 1.8×1011Ckg−1 the maximum velocity of the ejected electrons is

- 6×105ms−1
- 1.8×105ms−1
- 8×105ms−1
- 1.8×106ms−1

**Q.**

Threshold frequency for a metal is 1015Hz. Light of λ=4000∘A falls on its surface. Which of the following statements is correct

No photoelectric emission takes place

Photo-electrons come out with zero speed

Photo-electrons come out with 105 m/sec speed

Photo-electrons come out with 103 m/sec speed

**Q.**

What happens to ejected photoelectrons KE if the wavelength of incident light decreases?