MHT CET 2025 20th April Evening Shift | Dual Nature of Radiation Question 1 | Physics

On a photosensitive material, when frequency of incident radiation is increased by $20 \%$, maximum kinetic energy of emitted photoelectrons increases from 0.4 eV to 0.7 eV . The work function of the material is

3.5 eV

1.1 eV

0.48 eV

0.22 eV

MHT CET 2025 20th April Evening Shift

MCQ (Single Correct Answer)

-0

A light of wavelength $\lambda$ is incident on a photosensitive surface of negligible work function. The photoelectrons emitted from the surface have de-Broglie wavelength $\lambda_1$. Then ratio $\lambda: \lambda_1{ }^2$ is

( $\mathrm{h}=$ Planck's constant, $\mathrm{c}=$ velocity of light, $\mathrm{m}=$ mass of electron)

$4 \mathrm{mc}: \mathrm{h}$

$\quad 2 c: h$

$2 \mathrm{mc}: \mathrm{h}$

$2 \mathrm{mh}: \mathrm{c}$

MHT CET 2025 20th April Morning Shift

MCQ (Single Correct Answer)

-0

Light of wavelength ' $\lambda$ ' falls on a metal having work function $\frac{\mathrm{hc}}{\lambda_0}$. Photoelectric effect will take place only if ( $\lambda_0$ is the threshold wavelength)

$\lambda \geq \lambda_0$

$\lambda \geq 2 \lambda_0$

$\lambda \leq \lambda_0$

$\lambda=4 \lambda_0$

MHT CET 2025 20th April Morning Shift

MCQ (Single Correct Answer)

-0

A parallel beam of light is incident normally on a plane surface absorbing $50 \%$ of the light and reflecting the rest. If the incident beam carries 90 W of power, the force exerted by it on the surface is ( $\mathrm{C}=$ velocity of light in air $=3 \times 10^8 \mathrm{~m} / \mathrm{s}$ )

$4.5 \times 10^{-7} \mathrm{~N}$

$1.5 \times 10^{-7} \mathrm{~N}$

$3 \times 10^{-7} \mathrm{~N}$

$9 \times 10^{-7} \mathrm{~N}$

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