Question 236: Dual Nature of Matter and Radiation

Question

A photocell is illuminated by a small bright source placed $$1$$ $$m$$ away. When the same source of light is placed $${1 \over 2}$$ $$m$$ away, the number of electrons emitted by photo-cathode would

Accepted Answer

$$I \propto {1 \over {{r^2}}};{{{I_1}} \over {{I_2}}} = {\left( {{{{r_2}} \over {{r_1}}}} ight)^2} = {1 \over 4}$$
$${I_2} 	o 4\,\,$$ times $${I_1}$$
When intensity becomes 4 times, no. of photoelectrons emitted would increase by $$4$$ times, since number of electrons emitted per second is directly proportional to intensity.

Answer

increases by a factor of $$4$$

Answer

decreases by a factor of $$4$$

Answer

increases by a factor of $$2$$

Answer

decreases by a factor of $$2$$

Dual Nature of Matter and Radiation

A photocell is illuminated by a small bright source placed $1 m away. When the same source of light is placed {1 \over 2} m$ away, the number of electrons emitted by photo-cathode would

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