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 × 10Z (where 1 < A

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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 :

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Energy of photon $\approx \frac{12420}{200} ev = 6 .2 eV$

Maximum KE of a electron = 6.2 eV – 4.7 eV

When potential on surface of sphere becomes equal to 1.5V

$\frac{q}{4 {πε}_{0} r} = 1 .5 V \Rightarrow q = 1 .5 \times (4 {πε}_{0}) \times r$

No. of photoelectron emitted $n = \frac{1 .5 \times (4 {πε}_{0}) r}{1 .6 \times 10^{- 19}} = 1 .04 \times 10^{7}$

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