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Question:

An electron is moving in a circular path under the influence of a transverse magnetic field of 3.57 × 10⁻⁶ T. If the value of e/m is 1.76 × 10¹¹ C/kg, the frequency of revolution of the electron is?

6.28MHz

100 MHz

1 GHZ

62.8MHz

Solution:

Given : e/m = 1.76 × 10¹¹ C/kg
B = 3.57 × 10⁻⁶ T
Frequency of revolution ν = Bq/(2πm)
∴ ν = 3.57 × 10⁻⁶ × 1.76 × 10¹¹ /(2π)
= 1 × 10⁹ Hz
= 1 GHz