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JEE Main 202126 AugustEvening Shift
Exam
JEE Main
Year
2021
Date
26 August
Shift
Evening Shift
Subject
Physics
Chapter
Electromagnetic Waves

JEE Main 2021 · 26 August · Evening Shift · Physics · Electromagnetic Waves

A light beam is described by E = 800sinω(t - (x)/(c)) . An electron...

A light beam is described by E=800sinω(t−xc).E = 800sin\omega\left(t - \dfrac{x}{c}\right) . An electron is allowed to move normal to the propagation of light beam with a speed of 3×107ms−13 \times {10}^{7}{ms}^{- 1}. What is the maximum magnetic force exerted on the electron?

Options

  1. A1.28×10−21N1 . 28 \times {10}^{- 21}N
  2. B12.8×10−18N12 . 8 \times {10}^{- 18}N
  3. C1.28×10−18N1 . 28 \times {10}^{- 18}N
  4. D12.8×10−17N12 . 8 \times {10}^{- 17}N

Correct answer

B. 12.8×10−18N12 . 8 \times {10}^{- 18}N

Step-by-step solution

E0=800V{E}_{0} = 800V

B0=E0c=8003×108{B}_{0} = \dfrac{{E}_{0}}{c} = \dfrac{800}{3 \times {10}^{8}}

Fm=qvB0=1.6×10−19×3×107×8003×108{F}_{m} = qv{B}_{0} = \dfrac{1 . 6 \times {10}^{- 19} \times 3 \times {10}^{7} \times 800}{3 \times {10}^{8}}

=12.8×10−18N= 12 . 8 \times {10}^{- 18}N

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