Dual Nature Of Radiation And Matter Ques 44
44. A $5$ watt source emits monochromatic light of wavelength $5000 $ $\AA$. When placed $0.5$ $ m$ away, it liberates photoelectrons from a photosensitive metallic surface. When the source is moved to a distance of $1.0$ $ m$, the number of photoelectrons liberated will be reduced by a factor of
[2007]
(a) $8$
(b) $16$
(c) $2$
(d) $4$
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Answer:
Correct Answer: 44.(d)
Solution:
- (d) Number of emitted electrons $N_E \propto$ Intensity
$\propto \frac{1}{(\text{ Distance })^{2}}$
Therefore, as distance is doubled, $N_E$ decreases by $(1 / 4)$ times.
BETA
