Values of work function $({W}_{0})$ for a few metals are given below Metal $\mathrm{Li}$ $\mathrm{Na}$ $K$ $\mathrm{Mg}$ $\mathrm{Cu}$ $\mathrm{Ag}$ $\frac{{W}_{0}}{\mathrm{eV}}$ $2.42$ $2.3$ $2.25$ $3.7$ $4.8$ $4.3$ The number of metals which will show photoelectric effect when light of wavelength $400\mathrm{nm}$ falls on it is _____ Given: $h=6.6\times {10}^{–34}Js$ $c=3\times {10}^{8}{\mathrm{ms}}^{–1}$ $e=1.6\times {10}^{–19}C$

JEE Main 2023 — Chemistry Physical Chemistry

2023integereasy

Values of work function $({W}_{0})$ for a few metals are given below

Metal	$\mathrm{Li}$	$\mathrm{Na}$	$K$	$\mathrm{Mg}$	$\mathrm{Cu}$	$\mathrm{Ag}$
$\frac{{W}_{0}}{\mathrm{eV}}$	$2.42$	$2.3$	$2.25$	$3.7$	$4.8$	$4.3$

The number of metals which will show photoelectric effect when light of wavelength

400\mathrm{nm}

falls on it is _____

Given: $h=6.6\times {10}^{–34}Js$

$c=3\times {10}^{8}{\mathrm{ms}}^{–1}$

$e=1.6\times {10}^{–19}C$

Official previous-year question

Held on 12 Apr 2023 · Verified 6 Jul 2026.

Did you get this right?

Solution

The minimum amount of energy necessary to start the emission of electrons from a metal's surface is known as its work function. The work function is the minimum amount of energy required to remove an electron from a metal's surface to infinity.

Energy of incident photon $=\frac{hc}{\lambda }$

$=\frac{6.6\times {10}^{-34}\times 3\times {10}^{8}}{400\times {10}^{-9}}J$

$=\frac{6.6\times {10}^{-34}\times 3\times {10}^{8}}{400\times {10}^{-9}\times 1.6\times {10}^{-9}}\mathrm{eV}$

$=3.1\mathrm{eV}$

If radiation energy is greater than work function of metal, then metal show photo electric effect.

$\therefore \mathrm{Li},\mathrm{Na}$ and $K$ will show photoelectric effect.

Your note

JEE Main Physical Chemistry in other years

Physical Chemistry 2026 Physical Chemistry 2025 Physical Chemistry 2024 Physical Chemistry 2022 Physical Chemistry 2021 Physical Chemistry 2020 Physical Chemistry 2019 Physical Chemistry 2018 Physical Chemistry 2017 Physical Chemistry 2016 Physical Chemistry 2015 Physical Chemistry 2014

Keep practicing Physical Chemistry

Work through every JEE Main Physical Chemistry PYQ, year by year.

Browse all Chemistry topics

JEE Main 2023 — Chemistry Physical Chemistry

2023integereasy

Values of work function $({W}_{0})$ for a few metals are given below

Metal	$\mathrm{Li}$	$\mathrm{Na}$	$K$	$\mathrm{Mg}$	$\mathrm{Cu}$	$\mathrm{Ag}$
$\frac{{W}_{0}}{\mathrm{eV}}$	$2.42$	$2.3$	$2.25$	$3.7$	$4.8$	$4.3$

The number of metals which will show photoelectric effect when light of wavelength

400\mathrm{nm}

falls on it is _____

Given: $h=6.6\times {10}^{–34}Js$

$c=3\times {10}^{8}{\mathrm{ms}}^{–1}$

$e=1.6\times {10}^{–19}C$

Official previous-year question

Held on 12 Apr 2023 · Verified 6 Jul 2026.

Did you get this right?

Solution

Energy of incident photon $=\frac{hc}{\lambda }$

$=\frac{6.6\times {10}^{-34}\times 3\times {10}^{8}}{400\times {10}^{-9}}J$

$=\frac{6.6\times {10}^{-34}\times 3\times {10}^{8}}{400\times {10}^{-9}\times 1.6\times {10}^{-9}}\mathrm{eV}$

$=3.1\mathrm{eV}$

If radiation energy is greater than work function of metal, then metal show photo electric effect.

$\therefore \mathrm{Li},\mathrm{Na}$ and $K$ will show photoelectric effect.

Your note

JEE Main Physical Chemistry in other years

Keep practicing Physical Chemistry

Work through every JEE Main Physical Chemistry PYQ, year by year.

Browse all Chemistry topics

JEE Main 2023 — Chemistry Physical Chemistry

Did you get this right?

Solution

Your note

JEE Main Physical Chemistry in other years

More JEE Main Physical Chemistry questions

Other Chemistry topics for JEE Main

Organic Chemistry

Inorganic Chemistry

Keep practicing Physical Chemistry

JEE Main 2023 — Chemistry Physical Chemistry

Did you get this right?

Solution

Your note

JEE Main Physical Chemistry in other years

More JEE Main Physical Chemistry questions

Other Chemistry topics for JEE Main

Organic Chemistry

Inorganic Chemistry

Keep practicing Physical Chemistry