# In an Experiment on Photoelectric Effect, Light of Wavelength 400 Nm is Incident on a Cesium Plate at the Rate of 5.0 W. the Potential of the Collector Plate - Physics

Sum

In an experiment on photoelectric effect, light of wavelength 400 nm is incident on a cesium plate at the rate of 5.0 W. The potential of the collector plate is made sufficiently positive with respect to the emitter, so that the current reaches its saturation value. Assuming that on average, one out of every 106 photons is able to eject a photoelectron, find the photocurrent in the circuit.

#### Solution

Given:-

Wavelength of light, λ = 400 nm

Power, P = 5 W

Energy of photon,

E = (hc)/λ = (1242/400)  "eV"

Number of photons, n = P/E

n = (5 xx 400)/(1.6 xx 10^-19 xx 1242)

Number of electrons = 1 electron per 106 photons

Number of photoelectrons emitted,

n' = (5 xx 400)/(1.6 xx 1242 xx 10^-19 xx 10^6)

Photo electric current,

I = Number of electron xx Charge on electron

I = (5 xx 400)/(1.6 xx 1242 xx 10^-19 xx 10^6) xx 1.6 xx 10^-19

= 1.6 xx 10^-6  "A" = 1.6  "uA"

Concept: Photoelectric Effect and Wave Theory of Light
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#### APPEARS IN

HC Verma Class 11, Class 12 Concepts of Physics Vol. 2
Chapter 20 Photoelectric Effect and Wave-Particle Duality
Q 26 | Page 366