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Worksheet-1

Dual nature of light

1 Threshold wavelength for a metal having work function W 0 is X. What is the threshold
wavelength for the metal having work function 2W 0?
(a) 4λ
(b) 2λ
(c) λ/2
(d) λ/4
2 Radiations of frequency v are incident on a photosensitive metal. The maximum K.E. of the
photoelectrons is E. When the frequency of the incident radiation is doubled, what is the
maximum kinetic energy of the photoelectrons?
(a) 2E
(b) 4E
(c) E + hv
(d) E – hv
3 Maximum kinetic energy (Ek) of a photoelectron varies with frequency (v) of the incident
radiation as

4 The stopping potential V0 for photoelectric emission from a metal surface is plotted along y-
axis and frequency v of incident light along x-axis. A straight line is obtained as shown.