Answer:
The minimum intensity of light required is [tex]2.527\times 10^{-8} W[/tex].
Explanation:
Number of elections , N= [tex]1.40\times 10^{11} [/tex]
Energy of each electron = E = [tex]3.61\times 10^{-19} J[/tex]
Total energy of N elections = T
[tex]T=1.40\times 10^{11}\times 3.61\times 10^{-19} J=5.054\times 10^{-8} J [/tex]
The minimum intensity of light in Watts required to eject N electron sin 0.20 seconds :
[tex]\frac{5.054\times 10^{-8} J }{0.20 s}=2.527\times 10^{-8} W[/tex]
