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In an experiment, electrons are accelerated, from rest, by applying a voltage of 500 V. Calculate the radius of the path if a magnetic field 100 mT is then applied. [Charge of the electron = 1.6 × 10⁻¹⁹ C, mass of the electron = 9.1 × 10⁻³¹ kg]

1. 7.5 × 10⁻⁴ m
2. 7.5 × 10⁻³ m
3. 7.5 m
4. 7.5 × 10⁻² m

Correct answer: 7.5 × 10⁻⁴ m

Solution

The correct option is right because the radius of the path of an electron in a magnetic field is determined by the balance between the centripetal force and the magnetic force acting on the electron. By calculating the velocity gained from the applied voltage and using the formula for the radius of circular motion in a magnetic field, the result yields a radius of 7.5 × 10⁻⁴ m.

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