J J Science Academy

Subject: Physics
Topic: Modern Physics
SubTopic: Dual Nature of Radiation
Test Type: Unit Test
Marks: 30
Time: 45 min
Date: 2023-10-27
1. The work function of a metal is $3.3 \times 10^{-19} \text{ J}$. If light of frequency $8 \times 10^{14} \text{ Hz}$ is incident on the metal, the stopping potential will be (Planck's constant $h = 6.6 \times 10^{-34} \text{ Js}$, charge of electron $e = 1.6 \times 10^{-19} \text{ C}$):
(1) 0.5 V
(2) 1.0 V
(3) 1.5 V
(4) 2.0 V
2. An $\alpha$-particle and a proton are accelerated from rest by the same potential difference. Find the ratio of their de Broglie wavelengths.
(1) $1:\sqrt{2}$
(2) $1:2\sqrt{2}$
(3) $1:4$
(4) $1:8$
3. Which of the following statements is INCORRECT regarding the photoelectric effect?
(1) The maximum kinetic energy of photoelectrons depends on the frequency of incident light.
(2) The number of photoelectrons emitted is proportional to the intensity of incident light.
(3) Photoelectric emission is an instantaneous process.
(4) There is a time delay between the incidence of light and the emission of photoelectrons if the intensity is low.
4. A photon of energy $E$ ejects a photoelectron from a metal surface whose work function is $W$. If the de Broglie wavelength of the photoelectron is $\lambda$, then:
(1) $\lambda = \frac{h}{\sqrt{2m(E-W)}}$
(2) $\lambda = \frac{h}{\sqrt{2m(E+W)}}$
(3) $\lambda = \frac{h}{\sqrt{2mE}}$
(4) $\lambda = \frac{h}{\sqrt{2mW}}$