Question

Write three observable features of photoelectric effect that cannot be explain. How can einstein's photoelectric equation used to describe these three features

Answer 1

3 observations r - (1) intensity , (2) threshold freq. (3)K.E.max .

As u know , Einstein eq. - { K.E.max = 1/2 mv(v)max }

So , he explain on the basis of this eq.

(1) INTENSITY = inc. the intensity means no. Of photos incidenting per sec. inc. As each photon of suitable energy can eject an e- , hence no.of photon e-s emitted per second will inc.with inc. in intensity.

(2)THRESHOLD FREQ. = If v is less than v•

Then ,K.E.max = -ve { impossible}

Here , v= freq given

v•= threshold freq.

Hence , no emissions take place below threshold freq.

(3)K.E.max=

When v is greater than v•

Then from einstein eq. K.E.max directly proportional to v.

Which shows , that threshold freq., K.E.max depends on freq.