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A uniform magnetic field acts at right angles to the direction of motion of an electron. As a result, the electron moves in a circular path of radius \( 2 \, \text{cm} \). If the speed of electron is doubled, then the radius of the circular path will be
- 2.0 cm
- 0.5 cm
- 4.0 cm
- 1.0 cm
Correct answer: 4.0 cm
Solution
The radius of the circular path in a magnetic field is directly proportional to the speed of the charged particle. Doubling the speed of the electron will double the radius, making it 4.0 cm.
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