A charged particle is moving in a circular orbit of radius 6 cm with a uniform speed of 3 x 10⁶ m/s under the action of a uniform magnetic field 2 x 10⁻⁴ Wb/m² at right angles to the plane of the orbit. The charge to mass ratio of the particle is:
Correct answer: B. 2.5 x 10¹¹ C/kg
- A. 5 x 10⁹ C/kg
- B. 2.5 x 10¹¹ C/kg
- C. 5 x 10¹¹ C/kg
- D. 5 x 10¹² C/kg
Explanation
Magnetic force provides the centripetal force for circular orbit, so qvB = mv²/r. Rearranging for charge-to-mass ratio gives q/m = v/(Br) = 3×10⁶ / (2×10⁻⁴ × 0.06) = 2.5×10¹¹ C/kg.
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About Electromagnetism
Magnetic flux density and magnetic flux describe the strength of a magnetic field and the field passing through a surface. A charged particle moving through a magnetic field experiences a force perpendicular to its velocity and may follow circular or helical motion, depending on the angle between velocity and field.
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