A metal plate of area 1 × 10 - 4 m 2 is illuminated by a radiation of intensity 16 m i l l i W m 2 . The work function of the metal is 5 e V . The energy of the incident photons is 10 e V and only 10

Question

A metal plate of area 1 × 10 - 4 m 2 is illuminated by a radiation of intensity 16 m i l l i W m 2 . The work function of the metal is 5 e V . The energy of the incident photons is 10 e V and only 10 % of it produces photo electrons. The number of emitted photo electron per second and their maximum energy, respectively, will be: 1 e V = 1.6 × 10 - 19 J

TestHub · Accepted Answer

Einstein's photoelectric equation
Maximum $K E = \frac{h C}{λ} - ϕ$

$= 10 - 5$

$= 5 e V$

Intensity $I = \frac{(N_{p}) \frac{h C}{λ}}{t A} \Rightarrow \frac{N_{p}}{t} = \frac{I A}{(\frac{h C}{λ})}$

and number of electrons per second. $= (\frac{N_{p}}{t}) \times 10 %$

$= (\frac{I A}{\frac{h C}{λ}}) \times \frac{1}{10} = \frac{16 \times 10^{- 3} \times 10^{- 4}}{10 \times 1.6 \times 10^{- 19} \times 10}$

$= 10^{11}$ per sec

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