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.
Discussion Forum Latest Questions
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 (A) 1.2 µT, vertically upward. Using the Biot-Savart law, the magnetic field at a distance of 2.5 m from a current of 15 A is B = μ0l/2πr. The direction, by the right-hand rule, is vertically ...
The correct answer is (D) 6 A in the clockwise direction. To nullify the magnetic field at the common center, the magnetic fields produced by both loops must be equal and opposite. Using the ratio of radii and currents, loop ...