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# Question about PHOTOELLECTRIC EFFECT.?

The given is the graph of - frequency of light incident on a metal plate vs kinetic energy of emitted electron.

i. What is the threshold frequency?

ii. If light of 1000Å wavelength is incident on the plate, will electron be emitted?

### 1 Answer

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- RealProLv 76 months ago
E_k = h*f - W

So the slope of the line is h and we are looking for the f-intercept f0.

Using the pair E_k = 5×10^15 and f = 1.2 * 1.6×10^-19 J

Definition of slope

h = (E_k - 0) / (f - f0)

f0 = f - (E_k / h) =

= 2.1×10^15 Hz

1000 Å is frequency of 3×10^15 Hz which is more than f0 so it is enough energy per photon to trigger the effect.

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