JEE Mains · Physics · STD 12 - Moving charges and magnetism
- JEE Mains 2019
- Medium
- MCQ
In an experiment, electrons are accelerated, from rest, by applying, a voltage of \(500 \,V.\) Calculate the radius of the path if a magnetic field \(100\,mT\) is then applied. [Charge of the electron \(= 1.6 \times 10^{-19}\,C\) Mass of the electron \(= 9.1 \times 10^{-31}\,kg\) ]
Pick an option to check your answer.
Answer & Solution
Correct Answer
(D) \(7.5\times 10^{-4}\,m\)
Step-by-step Solution
Detailed explanation
\({{\text{k}}_{\text{e}}} = \frac{{{{\text{p}}^2}}}{{2{{\text{M}}_{\text{e}}}}} = 500\,{\text{e}} \ldots ({\text{i}})\)
\(\ \,{\text{R}} = \frac{{\text{p}}}{{{\text{eB}}}} = \frac{{1000{{\text{m}}_{\text{e}}}{\text{e}}}}{{{\text{eB}}}}\)
\( = \frac{{1010 \times 9.1 \times {{10}^{ - 31}}}}{{1.6 \times {{10}^{ - 19}}}}\)
\( = 100 \times 7.541 \times {10^{ - 6}}\)
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