Question

The following diagram in Fig. 10.44 shows a coil X connected to a sensitive centre –zero galvanometer G and a coil P connected to a battery through a switch *.

(a) Describe the observation when the switch * is (i) closed suddenly, (ii) then kept closed, (iii) finally opened.

(b) Name and state the law which explains the above observations.

Answer 1

(a)

(i) When switch is closed suddenly, the galvanometer needle deflects for a moment.

(ii) If switch is kept closed then galvanometer needle returns to zero.

(iii) If switch is opened again then galvanometer needle deflects again but in opposite to the direction of deflection in case (a).

(b) This can be explained by Faraday'* law which states that whenever there is change in the magnetic flux linked with a coil, an e.m.f. is induced. The induced e.m.f. lasts as long as there is a change in the magnetic flux linked with the coil.