Explain the difficulties occurred by using galvanometer directly as ammeter.

Explanation

1. Galvanometer can.t use directly as a ammeter in circuit. This is for two reasons.

(i) (i) Galvanometer is a very sensitive device, it gives a full scale deflection for a current of the order of `muA`.
(ii) For measuring currents the galvanometer has to be connected in series and as it has a large resistance, this will change the value of the current in the circuit.
Original value `I=V/R` and after
connection of G it become `I.=V/(R+G)`.
2. If galvanometer is used to measure the p.d. in the circuit of larger p.d. thin copper wire of galvanometer is likely to be burnt due to large quantity of produced heat according to `I^(2)Rt`.