A silver sphere of radius 1 ~cm and work function 4.7 eV is suspended from an insulating thread in free-space. It is under continuous illumination of 200 ~nm wavelength light. As photoelectrons are emitted, the sphere gets charged and acquires a potential. The maximum number of photoelectrons emitted from the sphere is A 10^Z (where 1 < A < 10 ). The value of Z is

Step-by-step solution

Photoemission will stop when potential on silver sphere becomes equal to the stopping potential. h c -W=e V₀ Here, V₀= 1 4 ₀ n e r aligned & ( 1240 1200 eV )-(4.7 eV ) &= 9 10^9 n 1.6 10⁻¹⁹ 10⁻² &(6.2-4.7)= 9 10^9 n 1.6 10⁻¹⁹ 10⁻² & or n= 1.5 10⁻² 9 1.6 10⁻¹⁰ =1.04 10^7 aligned Answer is 7 . Analysis of Question (i) Question is moderately difficult. (ii) In eV ₀ if we substitute the value of e=1.6 10⁻¹⁹ C , then answer is in J. If we leave it then, answer is in e ~V .