To remove the tension in the supporting strings, the magnetic force (BIl) should balance the gravitational force (mg). Therefore, equating BIl = mg, the current required is I = mg/Bl. Hence, the Correct answer is (c) mg/lB.

A current-carrying wire kept in a uniform magnetic field will experience a maximum force when it is perpendicular to the magnetic field. This is because the magnetic force is given by F = Bill sin θ and sin 90° = ...

If an ammeter is to be used as a voltmeter, a high resistance must be connected in series with it. This combination limits the current through the ammeter while allowing it to measure the potential difference accurately.

The correct answer is (C) Helical with its axis parallel to X-axis. The electric field exerts a force along the X-axis, while the magnetic field causes circular motion in the YZ plane. The superposition of linear and circular motions results ...

The magnetic field due to a straight current-carrying wire is given by B = μ0I/2πr​ . Substituting μ0 = 4π × 10⁻⁷ , I = 5 A and r = 0.1 m, B = 1 × 10⁻⁵ T. Using the ...