Question

1) a. How can a galvanometer be used to determine emf in a circuit?

b. What two factors determine the direction of the induced emf?

c. When a bar magnet is thrust into one end of a coil, is the pole produced at the end of the coil the same as, or opposite to the pole of the bar magnet? Does the action of these two magnetic fields tend to oppose the motion of the bar magnet or assist it?

please I need some type of detailed explanation

Answer 1

When the magnet shown below is moved “towards” the coil, the pointer or needle of the Galvanometer, which is basically a very sensitive center, will deflect away from its center position in one direction only. When the magnet stops moving and is held stationary with regards to the coil the needle of the galvanometer returns back to zero as there is no physical movement of the magnetic field. This is as per Michael Faraday’s law of electromagnetic induction which states: “that a voltage is induced in a circuit whenever relative motion exists between a conductor and a magnetic field and that the magnitude of this voltage is proportional to the rate of change of the flux”.

Factors on which amount and direction of deflection depends are as under-

1) Increasing the number of turns of wire in the coil. – By increasing the amount of individual conductors cutting through the magnetic field, the amount of induced emf produced will be the sum of all the individual loops of the coil.

2) Increasing the speed of the relative motion between the coil and the magnet. – If the same coil of wire passed through the same magnetic field but its speed or velocity is increased, the wire will cut the lines of flux at a faster rate so induced emf would be produced.

3) Increasing the strength of the magnetic field. – If the same coil of wire is moved at the same speed through a stronger magnetic field, there will be more emf produced because there are more lines of force to cut.

b)