Question

When a metallic surface is illuminated with light of wave length (lambda),the stopping potential is X volt.when the same surface is illuminated of wave length 2lambda, stopping potential is X/3 threshold wave length for the metallic surface is....

Answer 1

Answer on Question #50752, Physics, Nuclear Physics

When a metallic surface is illuminated with light of wave length (lambda), the stopping potential is $X$ volt. When the same surface is illuminated of wave length 2lambda, stopping potential is $X/3$.

Threshold wave length for the metallic surface is...

Answer:

(https://en.wikipedia.org/wiki/Photoelectric_effect)

Will use photoelectric effect equation for this problem:

Energy of illumination photon $\frac{hc}{\lambda}$ equal to sum of work function $\varphi$ and stopping opposite work $eX$.

1. $\frac{hc}{\lambda} = \varphi + eX$

2. $\frac{hc}{2\lambda} = \varphi + e\frac{X}{3}$

This system gives us the result:

$$\frac{hc}{4\lambda} = \varphi$$

work function $\varphi$ may be denoted in mean of trash hold wavelength:

$$\varphi = \frac{hc}{\lambda_t}$$

It is obvious that:

$$\lambda_t = 4\lambda$$

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