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Wave Optics

Question
CBSEENPH12038452

The threshold frequency for a certain metal is 3.3 x 1014 Hz. If light of frequency 8.2 x 1014 Hz is incident on the metal, predict the cut-off voltage for the photoelectric emission.

Solution
Given,
Threshold frequency, v
0 = 3.3 x 1014 Hz
Frequency of light, v = 8.2 x 10
14 Hz
Planck's constant, h = 6.63 x 10
–34 Js

Using Einstein's photoelectric equation,
           12mv2max = h(v-v0) = eV0

                  V0 = h(v-v0)e
                  V0 = 6.62 × 10-341.6 × 10-19(8.2 × 1014 - 3.3 × 1014) 

i.e.,                V0 = 2.03 V. 

is the required cut=off voltage for photoelectric emission.

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