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(i) State two important features of Eins...

(i) State two important features of Einstein's photoelectric equation.
(ii) Radiation of frequency `10^(15)Hz` is incident on two photosensitive surface `P` and `Q`. There is no photoemission from surface `P`. Photoemission occurs from `Q` but photoelectrons have zero kinetic energy. Explain these observation and find the value of work function for surface `Q`.

Text Solution

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(i) Einstein photoelectric equation is :
`hv = hv_(0) + 1/2 mv^(2)`
i.e, Energy of photolength (hv) is used in photoelectric current is proportial to the intensity .
1. Liberating the electron from metal surface is called work function `(hv_(0))` and
2. Importing KE to the rejected electrons.
It is explains why photoelecric curernt is proportional to intensity jand `(vgt v_(0))`, however, the emission of electrons are instaneous. Low intensity of incident radiation does not mean delay in emision.
(ii) `lambda = c/f = (3 xx 10^(6))/(10^(15)) = 300nm` , Energy of rad. `= (1240)/(300) = 4.13eV`
The work function of P is higher so there is no ejection from P.
Q emits electron so its work function is `10^(15) J` as there is `380 K.E.` of emitted electron from Q. Work function of `Q = 4.133eV`.
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