Work, Power and EnergyHard
Question
When a metal surface is illuminated by light of wavelengths 400 nm and 250 nm, the maximum velocities of the photoelectrons ejected are v and 2v respectively. The work function of the metal is (h = Planck′s constant, c = velocity of light in air)
Options
A.2 hc × 106 J
B.1.5 hc × 106 J
C.hc × 106 J
D.0.5 hc × 106 J
Solution
By using 
= W0 + 
mv2
⇒
= W0 + 
mv2 .....(i)
and
= W0 + 
m(2v)2 .....(ii)
On solving (i) and (ii)
mv2 = 
.....(iii)
From equation (i) and (iii) W0 = 2hc × 106 J
= W0 + mv2 ⇒
= W0 + mv2 .....(i)and
= W0 + m(2v)2 .....(ii)On solving (i) and (ii)
mv2 = .....(iii)From equation (i) and (iii) W0 = 2hc × 106 J
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