A metallic bob A oscillates throgh the space between the poles of an electromagnet . The oscillation are more quickly damped when the circuit is on, as compared to the case when the circuit is off. Explain.

In an oscillator when the signal from the output circuit is applied to input of the circuit then it called

A small coil is introduced between the poles of an electromagnet so that its axis coincides with the magnetic field direction. The number of turns is n and the cross sectional area of the coil is A . When the coil turns through 180^(@) about its diameter, the charge flowing through the coil is Q . the total resistance of the circuit is R . what is the magnitude of the magnetic induction?

A small coil is introduced between the poles of an electromagnet so that its axis coincides with the magnetic field direction. The cross-sectional area of the coil is equal to S = 3.0 mm^2 , the number of turns is N = 60 . When the coil turns through 180^@ about its diameter, a galvanometer connected to the coil indicates a charge q = 4.5muC flowing through it. Find the magnetic induction magnitude between the poles, provided the total resistance of the electric circuit equals R = 40 Omega .

When an ammeter is put in series of a circuit, does it record slightly less or more than the actual current in the circuit ? Explain.

The motion of copper plate is damped when it is allowed to oscillate between the two poles of a magnet. What is the cause of this damping?