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# Test: Photoelectric Effect

## 10 Questions MCQ Test Physics Class 12 | Test: Photoelectric Effect

Description
This mock test of Test: Photoelectric Effect for Class 12 helps you for every Class 12 entrance exam. This contains 10 Multiple Choice Questions for Class 12 Test: Photoelectric Effect (mcq) to study with solutions a complete question bank. The solved questions answers in this Test: Photoelectric Effect quiz give you a good mix of easy questions and tough questions. Class 12 students definitely take this Test: Photoelectric Effect exercise for a better result in the exam. You can find other Test: Photoelectric Effect extra questions, long questions & short questions for Class 12 on EduRev as well by searching above.
QUESTION: 1

Solution:
QUESTION: 2

Solution:
QUESTION: 3

### Sodium surface is illuminated by ultraviolet and visible radiation successively and the stopping potential determined. The stopping potential is

Solution:

λ for U.V is less than λ for visible light
ν for U.V is greater than ν for visible light
∴ potential is greater for U.V light.
as K.Eα1​/λ

QUESTION: 4

Light of frequency 1.5 times the threshold frequency is incident on a photosensitive material .If the frequency is halved and the intensity is doubled, the photoelectric current becomes​

Solution:

When the frequency of incident light is halved of its original value i.e. 1.5v0​ then it becomes less than the threshold value. In that case no photoelectric effect takes place. No photoelectrons would be emitted. The photoelectric current becomes zero.

QUESTION: 5

Light of wavelength 4000 Â is incident on a metal of work function 3.2 x 10-19 J. What is the maximum kinetic energy of the emitted electron?​

Solution:

Given,
λ= 4000 Å ;W•= 3.2× 10-19 j
as we know that
K.E = (hc/ λ) - W•
= (6.6× 10-34 × 3 × 10-19/ 4000×10-10 )- 3.20× 10-19
= 1.75 × 10-19

QUESTION: 6

Light from a bulb is falling on a wooden table but no photo electrons are emitted as

Solution:

It is because the work function of wood is more than the energy of the incident photons of light. Hence, photoelectrons are not emitted from the wooden table.

QUESTION: 7

Photons of energy 6eV are incident on a potassium surface of a work function 2.1 eV. What is the stopping potential?​

Solution:

From photo-electric equation,   eV0​= E−φ
eV0​=(6−2.1)eV
V0​= 3.9 V
stopping potential is a negative potential to stop e- at saturated current .

QUESTION: 8

The energy of the incident photon is 20 eV and the work function of the photosensitive metal is 10 eV. What is the stopping potential?​

Solution:
QUESTION: 9

Light of two different frequencies whose photons have energies of 1eV and 2.5 eV respectively successively illuminate a metal of work function 0.5eV. The ratio of maximum speed of emitted electrons is​

Solution:
QUESTION: 10

A photo-sensitive material would emit electrons, if excited by photons beyond a threshold. To overcome the threshold, one would increase the:

Solution: