Physics
(a) Describe briefly one way of producing an induced e.m.f.
(b) State one factor that determines the magnitude of induced e.m.f. in part (a) above.
(c) What factor determines the direction of induced e.m.f. in part (a) above?
Answer
When there is a relative motion between the coil and magnet, magnetic flux linked with the coil changes. As shown in figure b, the coil is moved towards the north pole of magnet, so the magnetic flux through the coil increases. Similarly, if the coil is moved away from the north pole of magnet, the magnetic flux through the coil decreases. Due to change in the magnetic flux linked with the coil, an e.m.f. is induced in the coil. The induced e.m.f. causes a current to flow in the coil if the circuit of coil is closed.
(b) The magnitude of induced e.m.f. depends on the rate of change of magnetic flux linked with each turn.
(c) The direction of induced e.m.f. depends on whether there is an increase or decrease in the magnetic flux. It can be determined by any of the following two rules (i) Fleming's right hand rule, (ii) Lenz's law.
Related Questions
The diagram, shows a fixed coil of several turns connected to a centre zero galvanometer G and a magnet NS which can move in the direction shown in the diagram.
(a) Describe the observation in the galvanometer if (i) the magnet is moved rapidly, (ii) the magnet is kept stationary after it has moved into the coil, (iii) the magnet is then rapidly pulled out of the coil.
(b) How would the observation in (i) of part (a) change if a more powerful magnet is used?
Explain how does the Lenz's law show the conservation of energy in the phenomenon of electromagnetic induction.
(a) What is electromagnetic induction?
(b) Describe one experiment to demonstrate the phenomenon of electromagnetic induction.
The diagram shows a coil of several turns of copper wire near a magnet NS. The coil is moved in the direction of arrow shown in the diagram.
(i) In what direction does the induced current flow in the coil?
(ii) Name the law used to arrive at the conclusion in part (i).
(iii) How would the current in coil be altered if:
- the coil has twice the number of turns,
- the coil was made to move three times fast?