Dual Nature Of Light Question 251
Question: The work function for tungsten and sodium are 4.5 eV and 2.3 eV respectively. If the threshold wavelength $ \lambda $ for sodium is $ 5460{AA} $ , the value of $ \lambda $ for tungsten is [MP PET 1990]
Options:
A) 5893 Å
B) 10683 Å
C) 2791 Å
D) 528 Å
Show Answer
Answer:
Correct Answer: C
Solution:
Since $ W_{0}=\frac{hc}{{\lambda_{0}}} $ ;
$ \therefore \ \frac{{{(W_{0})}{T}}}{{{(W{0})}{Na}}}=\frac{{\lambda{Na}}}{{\lambda_{T}}} $ or $ {\lambda_{T}}=\frac{{\lambda_{Na}}\times {{(W_{0})}{Na}}}{{{(W{0})}_{T}}} $ $ =\frac{5460\times 2.3}{4.5}=2791\ {\AA} $
BETA
