Dual Nature Of Light Question 296
Question: The work functions of metals A and B are in the ratio 1 : 2. If light of frequencies $ f $ and $ 2f $ are incident on the surfaces of A and B respectively, the ratio of the maximum kinetic energies of photoelectrons emitted is (f is greater than threshold frequency of A, 2f is greater than threshold frequency of B) [EAMCET (Med.) 2000]
Options:
A) 1 : 1
B) 1 : 2
C) 1 : 3
D) 1 : 4
Show Answer
Answer:
Correct Answer: B
Solution:
$ E=W_{0}+{K_{\max }} $ ?..(i)
$ \Rightarrow hf=W_{A}+K_{A} $ ?..(ii) and $ 2hf=W_{B}+K_{B}=2W_{A}+K_{B} $ $ ( \because \frac{W_{A}}{W_{B}}=\frac{1}{2} ) $ Dividing equation (i) by (ii) $ \frac{1}{2}=\frac{W_{A}+K_{A}}{2W_{A}+K_{B}}\Rightarrow \frac{K_{A}}{K_{B}}=\frac{1}{2} $
BETA
