A particle having the same charge... | Moving Charges & Magnetism

JEE MAIN 2019

09-01-19 S2

Question

A particle having the same charge as of electron moves in a circular path of radius 0.5 cm under the influence of a magnetic field of 0.5 T . If an electric field of $100 \mathrm{~V} / \mathrm{m}$ makes it to move in a straight path, then the mass of the particle is (Given charge of electron $=1.6 \times 10^{-19} \mathrm{C}$ )

Select the correct option:

$9.1 \times 10^{-31} \mathrm{~kg}$

$1.6 \times 10^{-27} \mathrm{~kg}$

$1.6 \times 10^{-19} \mathrm{~kg}$

$2.0 \times 10^{-24} \mathrm{~kg}$

✓ Correct! Well done.

✗ Incorrect. Try again or view the solution.

Solution

$\begin{aligned} & e E=e V B \\ & R=\frac{m V}{e B} \Rightarrow V=\frac{\operatorname{ReB}}{m} \\ & \Rightarrow E=\frac{\operatorname{ReB}}{m} \cdot B \Rightarrow m=\frac{e B^2 R}{E} \\ & m=\frac{1.6 \times 10^{-19} \times(0.5)^2 \times 0.5 \times 10^{-2}}{100} \\ & =2.0 \times 10^{-24} \mathrm{~kg}\end{aligned}$

Question Tags

JEE Main

Physics

Easy

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