A silver sphere of radius 1 cm and work func | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(A) The energy of the incident photon is $E = \frac{hc}{\lambda} = \frac{1240 \ eV \cdot nm}{200 \ nm} = 6.2 \ eV$.The maximum kinetic energy of the e

Vedclass · Accepted Answer

$7$

Vedclass · Answer

(A) The energy of the incident photon is $E = \frac{hc}{\lambda} = \frac{1240 \ eV \cdot nm}{200 \ nm} = 6.2 \ eV$.The maximum kinetic energy of the emitted photoelectrons is $K_{max} = E - \phi = 6.2 \ eV - 4.7 \ eV = 1.5 \ eV$.As the sphere emits photoelectrons,it becomes positively charged and its potential $V$ increases. Emission stops when the potential $V$ is such that the energy required to remove an electron is equal to the maximum kinetic energy,i.e.,$eV = K_{max} = 1.5 \ eV$. Thus,$V = 1.5 \ V$.The potential of a sphere of radius $R$ with charge $q = ne$ is $V = \frac{kq}{R} = \frac{k(ne)}{R}$,where $n$ is the number of photoelectrons.Substituting the values: $1.5 = \frac{(9 	imes 10^9) 	imes n 	imes (1.6 	imes 10^{-19})}{10^{-2}}$.$1.5 = n 	imes 1.44 	imes 10^{-7} \implies n = \frac{1.5}{1.44} 	imes 10^7 \approx 1.04 	imes 10^7$.Given $n = A 	imes 10^Z$,we have $1.04 	imes 10^7 = A 	imes 10^Z$. Comparing,$Z = 7$.

Similar Questions

The threshold wavelength for the photoelectric effect on sodium is $5000\;\mathring{A}$. Its work function is:

Monochromatic light of wavelength $\lambda$ is incident on an isolated metal sphere of radius $a$. The threshold wavelength is $\lambda_0$,which is greater than $\lambda$. How many photoelectrons will be emitted before the emission of photoelectrons stops?

Radiation of wavelength $300 \ nm$ and intensity $100 \ W \ m^{-2}$ falls on the surface of a photosensitive material. If $2 \%$ of the incident photons produce photoelectrons,the number of photoelectrons emitted from an area of $2 \ cm^2$ of the surface per second is nearly:

The work functions of metal $A$ and $B$ are in the ratio $1: 2$. If light of frequency $f$ and $2f$ is incident on surface $A$ and $B$ respectively,then the ratio of the maximum kinetic energies of the emitted photoelectrons is:

Two identical metal plates show the photoelectric effect. Light of wavelength ${\lambda _A}$ falls on plate $A$ and light of wavelength ${\lambda _B}$ falls on plate $B$,where ${\lambda _A} = 2{\lambda _B}$. The maximum kinetic energy is:

Vedclass Test Series

Exam Paper Generator

Online Exam Module