Dual Nature Of Light Question 250
Question: Ultraviolet radiations of $ 6.2,eV $ falls on an aluminium surface (work function $ 4.2\ eV $ ). The kinetic energy in joules of the fastest electron emitted is approximately [MNR 1987; MP PET 1990; CBSE PMT 1993; Pb. PMT 2001; BVP 2003; Pb. PET 2004]
Options:
A) $ 3.2\times {{10}^{-21}} $
B) $ 3.2\times {{10}^{-19}} $
C) $ 3.2\times {{10}^{-17}} $
D) $ 3.2\times {{10}^{-15}} $
Show Answer
Answer:
Correct Answer: B
Solution:
$ {K_{\max }}(eV)=E,(eV)-W_{0},(eV) $ $ =6.2-4.2=2\ eV $
$ \therefore ,{K_{\max }}(Joules)= $ $ 2\times 1.6\times {{10}^{-19}}J=3.2\times {{10}^{-19}}J $
BETA
