When light of a given wavelength is incident | vedclass

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

Question

(A) According to Einstein's photoelectric equation: $K_{max} = \frac{hc}{\lambda} - \phi$,where $K_{max} = eV_s$.
For the first source: $\frac{hc

Vedclass · Accepted Answer

$1.72 	imes 10^{-7} \ m, 1.20 \ eV$

Vedclass · Answer

(A) According to Einstein's photoelectric equation: $K_{max} = \frac{hc}{\lambda} - \phi$,where $K_{max} = eV_s$.
For the first source: $\frac{hc}{\lambda} = \phi + 6.0 \ eV$ ... $(i)$
For the second source: $\frac{hc}{4\lambda} = \phi + 0.6 \ eV$ ... (ii)
Multiply equation (ii) by $4$: $\frac{hc}{\lambda} = 4\phi + 2.4 \ eV$ ... (iii)
Equating $(i)$ and (iii): $\phi + 6.0 = 4\phi + 2.4 \Rightarrow 3\phi = 3.6 \Rightarrow \phi = 1.2 \ eV$.
Substitute $\phi$ into $(i)$: $\frac{hc}{\lambda} = 1.2 + 6.0 = 7.2 \ eV$.
Given $hc = 1.24 	imes 10^{-6} \ J \ m = \frac{1.24 	imes 10^{-6}}{1.6 	imes 10^{-19}} \ eV \ m = 7.75 	imes 10^{12} \ eV \ m$ (approx) or using $hc = 1240 \ eV \ nm = 1.24 	imes 10^{-6} \ eV \ m$.
$\lambda = \frac{1.24 	imes 10^{-6}}{7.2} \approx 1.72 	imes 10^{-7} \ m$.

Similar Questions

When monochromatic light falls on a photo-sensitive metal,an electron is emitted with maximum velocity $1.6 \times 10^6 \ m/s$. Find the stopping potential.
[charge of electron $= 1.6 \times 10^{-19} \ C$,mass of electron $= 9 \times 10^{-31} \ kg$] (in $V$)

Two identical photo-cathodes receive light of frequencies $f_1$ and $f_2$. If the velocities of the photo-electrons (of mass $m$) coming out are $v_1$ and $v_2$ respectively,then:

The work function of Cesium is $2.27 eV$. The cut-off voltage which stops the emission of electrons from a cesium cathode irradiated with light of $600 nm$ wavelength is

When photons of energy $1 \ eV$ and $2.5 \ eV$ are incident on a metal surface with a work function of $0.5 \ eV$,what is the ratio of the maximum kinetic energies of the emitted photoelectrons?

If the energy of a photon is $25\, eV$ and the work function of the material is $7\, eV$,then the value of the stopping potential is :-................. $V$

Vedclass Test Series

Exam Paper Generator

Online Exam Module