Atomic Structure Question 385
Question: Calculate the velocity of ejected electron from the metal surface when light of frequency $ 2\times 10^{15}Hz $ fall on the metal surface and the threshold frequency is $ ~7\times 10^{14}Hz $ for metal-
Options:
A) $ ~1.37\times 10^{6} $
B) $ ~1.26\times 10^{6} $
C) $ 1.45\times 10^{7} $
D) $ ~1.37 \times 10^{7} $
Show Answer
Answer:
Correct Answer: A
Solution:
- $ \frac{1}{2}mv^{2}=hv-hv_0 $
$ \Rightarrow \frac{1}{2}mv^{2}=h(v-v_0) $
$ \Rightarrow v=\sqrt{\frac{2h}{m}(v-v_0)} $
$ =\sqrt{\frac{2\times 6.6\times {10^{-34}}}{9.1\times {10^{-31}}}}(2\times 10^{15}-7\times 10^{14}) $
$ =1.37\times 10^{6}ms^{1} $
