Dual Nature Of Radiation And Matter Ques 50
50. The work functions for metals $A, B$ and $C$ are respectively $1.92 $ $eV, 2.0$ $ eV$ and $5$ $ eV$. According to Einstein’s equation, the metals which will emit photoelectrons for a radiation of wavelength $4100$ $ \AA$ is/are
[2005]
(a) none
(b) $A$ only
(c) $A$ and $B$ only
(d) all three metals
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Answer:
Correct Answer: 50.(c)
Solution:
- (c) $E=\frac{h c}{\lambda}$ $\Rightarrow E=\frac{12375}{\lambda(\text{ in } A)}$ $ eV \Rightarrow E=\frac{12375}{4100}$ $ eV$
$\Rightarrow E \approx 3 $ $eV$
So, only metals having work function less than $3 $ $eV$ can emit photoelectrons for the incident radiation of wavelength $4100 $ $\AA$.
BETA
