Dual Nature Of Light Question 358
Question: Light of wavelength 180 nm ejects photoelectron from a plate of a metal whose work function is 2 eV. If a uniform magnetic field of $ 5\times {{10}^{-5}}T $ is applied parallel to plate, what would be the radius of the path followed by electrons ejected normally from the plate with maximum energy?
Options:
A) 1.239 m
B) 0.149 m
C) 3.182 m
D) 2.33 m
Show Answer
Answer:
Correct Answer: B
Solution:
[b] If $ {v_{\max }} $ is the speed of the fastest electron emitted from the metal surface, then $ \frac{hc}{\lambda }=W_{0}+\frac{1}{2}mv_{\max }^{2} $ $ \frac{( 6.63\times {{10}^{-34}} )\times ( 3\times 10^{8} )}{( 180\times {{10}^{-9}} )} $ The radius of the electron is given by $ r=\frac{mv}{qB}=\frac{( 9.1\times {{10}^{-31}} )\times ( 1.31\times 10^{6} )}{( 1.6\times {{10}^{-19}} )\times ( 5\times {{10}^{-9}} )}=0.149m $
BETA
