Dual Nature of Radiation and Matter - Result Question 46
48. When photons of energy $h v$ fall on an aluminium plate (of work function $E_0$ ), photoelectrons of maximum kinetic energy $K$ are ejected. If the frequency of the radiation is doubled, the maximum kinetic energy of the ejected photoelectrons will be
[2006]
(a) $2 K$
(b) $K$
(c) $K+h v$
(d) $K+E_0$
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Answer:
Correct Answer: 48. (c)
Solution:
- (c) Applying Einstein’s formula for photoelectricity
$h v=\phi+\frac{1}{2} m v^{2} ; \quad h v=\phi+K$
$\phi=h v-K$
If we use $2 v$ frequency then let the kinetic energy becomes $K^{\prime}$
So, $h .2 v=\phi+K$
$2 h v=h v-K+K^{\prime}$
$K^{\prime}=h v+K$
