JEE Main 2022 · 24 Jun · Shift 1 · Physics Q56

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PhysicsInteger+4 / -1Question 56 of 90

When light of frequency twice the threshold frequency is incident on the metal plate, the maximum velocity of emitted electron is $v_1$ . When the frequency of incident radiation is increased to five times the threshold value, the maximum velocity of emitted electron becomes $v_2$ . If $v_2=x\,v_1$ , the value of $x$ will be ______.

Your answer

Answer and worked solution

Official answer: 2

Einstein's equation. $\frac12mv^2=h\nu-h\nu_0$ .

Two cases. $\frac12mv_1^2=h\nu_0$ and $\frac12mv_2^2=4h\nu_0$ .

Ratio. $\dfrac{v_2}{v_1}=\sqrt4=2$ .

Answer: 2

Topics:Photoelectric effect

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JEE Main 2022 · 24 Jun · Shift 1, Physics question 56