Dual Nature of Radiation and Matter - Result Question 35
37. Light of two different frequencies whose photons have energies $1 eV$ and $2.5 eV$ respectively illuminate a metallic surface whose work function is $0.5 eV$ successively. Ratio of maximum speeds of emitted electrons will be
«««< HEAD
======= ####37. Light of two different frequencies whose photons have energies $1 eV$ and $2.5 eV$ respectively illuminate a metallic surface whose work function is $0.5 eV$ successively. Ratio of maximum speeds of emitted electrons will be
c3eec34ec6b1fad69db54a20ad4b2dca40c2aa54 (a) $1: 4$
(b) $1: 2$
(c) $1: 1$
(d) $1: 5$
[2011]
Show Answer
Answer:
Correct Answer: 37. (b)
Solution:
- (b) The maximum kinetic energy of emitted electrons is given by
$K . E=\phi-\phi_0$
$K . E_1=1 eV-0.5 eV=0.5 eV$
$K . E_2=2.5 eV-0.5 eV=2 eV$
$\therefore \frac{K \cdot E_1}{K \cdot E_2}=\frac{0.5 eV}{2 eV}=\frac{1}{4}$
$\Rightarrow \frac{v_1}{v_2}=\sqrt{\frac{1}{4}}=\frac{1}{2}$
