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JEE Mains · Physics · STD 12 - Electromagnetic waves
- JEE Mains 2020
- Medium
- MCQ
A particle of mass \(\mathrm{m}\) and charge \(\mathrm{q}\) has an initial velocity \(\overline{\mathrm{v}}=\mathrm{v}_{0} \hat{\mathrm{j}} .\) If an electric field \(\overrightarrow{\mathrm{E}}=\mathrm{E}_{0} \hat{\mathrm{i}}\) and magnetic field \(\overrightarrow{\mathrm{B}}=\mathrm{B}_{0} \hat{\mathrm{i}}\) act on the particle, its speed will double after a time:
Pick an option to check your answer.
Answer & Solution
Correct Answer
(C) \(\frac{\sqrt{3} m v_{0}}{q E_{0}}\)
Step-by-step Solution
Detailed explanation
\(\left(2 \mathrm{V}_{0}\right)^{2}=\mathrm{v}_{0}^{2}+\mathrm{v}_{\mathrm{x}}^{2}\)
\(v_{x}=\sqrt{3} v_{0}\)
\(\sqrt{3} \mathrm{v}_{0}=0+\frac{\mathrm{qE}_{0}}{\mathrm{m}} \mathrm{t}\)
\(\mathrm{t}=\frac{\sqrt{3} \mathrm{v}_{0} \mathrm{m}}{\mathrm{q} \mathrm{E}_{0}}\)
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