A violet laser ( ) is allowed to fall on a photo-cathode for

PHYSICS · Single correct · A Level · Physics · Particles and radiation · Particles and radiation

Problem

10\,\text{mW}

violet laser (

\lambda = 400\,\text{nm}

) is allowed to fall on a photo-cathode for

2\,\text{s}

. Assuming each photon ejects one electron, the total number of photoelectrons emitted is closest to (a)

2\times10^{16}

(b)

4\times10^{17}

(c)

4\times10^{16}

(d)

4\times10^{15}