Question

At t = 0, light of intensity $\frac{{10}^{12}photons}{s{m}^2}$ of energy 6eV per photon start falling on a plate with work function 2.5 eV. If area of the plate is $2\times {10}^{-4}{m}^2$ and for every ${10}^5$ photons one photoelectron is emitted, charge on the plate at t = 25 s is

• A. $8\times {10}^{-14}C$
• B. $4\times {10}^{-14}C$
• C. $12\times {10}^{-14}C$
• D. $16\times {10}^{-14}C$

Answer 1

The correct option is A $8\times {10}^{-14}C$

Number of emitted electrons =$\frac{{10}^{12}\times 2\times {10}^{-4}\times 25}{{10}^5}=5\times {10}^4$ electrons
$q=ne=8\times {10}^{-14}C$.