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← JEE Main 2017 · 8 Apr · Shift 1
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JEE Main 2017 · 8 Apr · Shift 1, Physics question 24

The maximum velocity of the photoelectrons emitted from the surface is v when light of frequency n falls on a metal surface. If the incident frequency is increased to 3n, the maximum velocity of the ejected photoelectrons will be :

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Answer and worked solution

Official answer: C

12mv2=hn−ϕ\frac12mv^2=hn-\phi and 12mv′2=3hn−ϕ=3(12mv2)+2ϕ\frac12mv'^2=3hn-\phi=3\left(\frac12mv^2\right)+2\phi. So v′2>3v2v'^2>3v^2 and v′>3vv'>\sqrt3v.