Dual Nature Of Light Question 239
Question: Threshold frequency for a metal is $ 10^{15} $ Hz. Light of $ \lambda =4000{AA} $ falls on its surface. Which of the following statements is correct
Options:
A) No photoelectric emission takes place
B) Photo-electrons come out with zero speed
C) Photo-electrons come out with 103 m/sec speed
D) Photo-electrons come out with 105 m/sec speed
Show Answer
Answer:
Correct Answer: A
Solution:
Frequency of light of wavelength $ (\lambda =4000\ {\AA}) $ is $ \nu =\frac{c}{\lambda }=\frac{3\times 10^{8}}{4000\times {{10}^{-10}}}=0.75\times 10^{15} $ which is less than the given threshold frequency. Hence no photoelectric emisssion takes place.
BETA
