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← JEE Main 2022 · 25 Jul · Shift 2
PhysicsSingle correct+4 / -1Question 41 of 90

JEE Main 2022 · 25 Jul · Shift 2, Physics question 41

An electron with energy 0.1 keV moves at right angle to the earth's magnetic field of 1×10−41\times10^{-4} Wbm−2^{-2}. The frequency of revolution of the electron will be (Take mass of electron =9.0×10−31=9.0\times10^{-31} kg)

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Answer and worked solution

Official answer: C

Cyclotron frequency eB2πm=1.6×10−19×10−42π×9×10−31≈2.8×106\dfrac{eB}{2\pi m}=\dfrac{1.6\times10^{-19}\times10^{-4}}{2\pi\times9\times10^{-31}}\approx2.8\times10^6 Hz (independent of energy).

(C)