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JEE Main 202125 JulyEvening Shift
Exam
JEE Main
Year
2021
Date
25 July
Shift
Evening Shift
Subject
Physics
Chapter
Magnetic Effects of Current

JEE Main 2021 · 25 July · Evening Shift · Physics · Magnetic Effects of Current

Two ions having same mass have charges in the ratio 1: 2 . They are...

Two ions having same mass have charges in the ratio 1:21: 2. They are projected normally in a uniform magnetic field with their speeds in the ratio 2:32: 3. The ratio of the radii of their circular trajectories is,

Options

  1. A1:41: 4
  2. B4:34: 3
  3. C3:13: 1
  4. D2:32: 3

Correct answer

B. 4:34: 3

Step-by-step solution

R=mvqB⇒R1R2=mv1q1Bmv2q2B=v1q1×q2v2=q2q1×v1v2R = \dfrac{mv}{qB} ⇒ \dfrac{{R}_{1}}{{R}_{2}} = \dfrac{\dfrac{m{v}_{1}}{{q}_{1}B}}{\dfrac{m{v}_{2}}{{q}_{2}B}} = \dfrac{{v}_{1}}{{q}_{1}} \times \dfrac{{q}_{2}}{{v}_{2}} = \dfrac{{q}_{2}}{{q}_{1}} \times \dfrac{{v}_{1}}{{v}_{2}}

=21×(23)=43= \dfrac{2}{1} \times \left(\dfrac{2}{3}\right) = \dfrac{4}{3}

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