Q. In a photoemissive cell with executing wavelength , the fastest electron has speed . If the exciting wavelength is changed to , the speed of fastest emitted electron will be

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A

Greater than

B

C

D

Less than

Solution:

According to photoelectric equation,

When wavelength is and velocity v, then
..... (i)
When wavelength is and velocity is then
...... (ii
Divide equation (ii) by equation (i), we get

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