JEE Main 2022 · 28 Jun · Shift 2 · Physics Q47

← JEE Main 2022 · 28 Jun · Shift 2

PhysicsSingle correct+4 / -1Question 47 of 90

Let $K_1$ and $K_2$ be the maximum kinetic energies of photo-electrons emitted when two monochromatic beams of wavelength $\lambda_1$ and $\lambda_2$ , respectively are incident on a metallic surface. If $\lambda_1=3\lambda_2$ then :

K_1>\dfrac{K_2}3

K_1<\dfrac{K_2}3

K_1=\dfrac{K_2}3

K_2=\dfrac{K_1}3

Answer and worked solution

Official answer: B

Einstein's equation. $K_1=\dfrac{hc}{3\lambda_2}-\phi$ and $\dfrac{K_2}3=\dfrac{hc}{3\lambda_2}-\dfrac\phi3$ . Since $\phi>\frac\phi3$ , $K_1<\frac{K_2}3$ .

(B)

Topics:Photoelectric effect

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JEE Main 2022 · 28 Jun · Shift 2, Physics question 47