Question

Light of wavelength $5000A$ and intensity $3.98nW/c{m}^2$ is incident on a light sensitive surface. If 1% photons of incident light cause emission of the photoelectrons, then how many electrons will be emitted from $l{m}^2$ area of the surface in one second?

• A. ${10}^{16}$
• B. ${10}^{18}$
• C. ${10}^{20}$
• D. ${10}^{22}$

Answer 1

The correct option is A ${10}^{16}$

If only $1$% photons cause an electron emission, then the no. of electrons emitted per second per unit area from surface is

$N_e=0.1N_r=\frac{0.01\times 39.3\times 5000\times {10}^{-10}}{3\times {10}^8\times 6.63\times {10}^{-34}}$

$N_e\approx {10}^{16}{m}^{-2}{s}^1$