State two factors by hich a tangent galvanometer can be made more senesitive. WHy is a tangent galvanometer not considered to be practically a very useful instrument?

Which are the two required fields in a tangent galvanometer?

State the demerits of Tangent Galvanometer.

Give two factors by which voltage sensitivity of a moving coil galvanometer can be increased?

Give two factors by which the current sensitivity of a moving coil galvanometer can be increased.

State two properties of the material of the wire used for suspension of the coil in a moving coil galvanometer?

Why can we not use the ordinary moving coil galvanometer for measureing a.c. current and voltage?

Two tangent galvanometers have circular coils of same radii differing only in the number of turns. They are connected in series. WHen a a steady current is passed in the circuit, the mean deflections of galvanometer are theta_1 and theta_2 . deduce an expression for the ratio of number of turns of the galvanometer.

Why is pure ironnot used for making permanent magnets? Name one material used for making permanent magnets. State two example of electrical instruments made by using permanent magnets.