JEE Mains · Physics · STD 12 - Electromagnetic waves
- JEE Mains 2020
- Medium
- MCQ
An electron is constrained to move along the \(y-\)axis with a speed of \(0.1\, c\) (c is the speed of light) in the presence of electromagnetic wave, whose electric field is \(\overrightarrow{ E }=30 \hat{ j } \sin \left(1.5 \times 10^{7} t -5 \times 10^{-2} x \right)\, V / m\) The maximum magnetic force experienced by the electron will be: (given \(c=3 \times 10^{8}\, ms ^{-1}\) and electron charge \(\left.=1.6 \times 10^{-19} C \right)\)
Pick an option to check your answer.
Answer & Solution
Correct Answer
(B) \(4.8 \times 10^{-19} N\)
Step-by-step Solution
Detailed explanation
\(\Rightarrow E =\overrightarrow{ E }=30 \hat{ j } \sin \left(1.5 \times 10^{7} t -5 \times 10^{-2} x \right) V / m\)
\(\Rightarrow B \Rightarrow E / V \Rightarrow \frac{30}{1.5 \times 10^{7}} \times 5 \times 10^{-2}\)
\(\Rightarrow 10^{-7}\) Tesla
\(\Rightarrow F _{ mag }= q (\overrightarrow{ V } \times \overrightarrow{ B })=| q VB |\)
\(=1.6 \times 10^{-19} \times 0.1 \times 3 \times 10^{8} \times 10^{-7}\)
\(=4.8 \times 10^{-19} N\)
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