JEE Main 2022 · 27 Jul · Shift 1 · Physics Q45

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PhysicsSingle correct+4 / -1Question 45 of 90

A beam of light travelling along X-axis is described by the electric field $E_y=900\sin\omega(t-x/c)$ . The ratio of electric force to magnetic force on a charge q moving along Y-axis with a speed of $3\times10^7$ ms $^{-1}$ will be :

(Given speed of light = $3\times10^8$ ms $^{-1}$ )

1:1

1:10

10:1

1:2

Answer and worked solution

Official answer: C

$B=\frac Ec$ , so $\frac{F_E}{F_B}=\frac{qE}{qvE/c}=\frac cv=10$ .

(C)

Topics:Properties of EM waves Force on a moving charge

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JEE Main 2022 · 27 Jul · Shift 1, Physics question 45