Explain the difficulties encountered when using a galvanometer directly as an ammeter.

(N/A) galvanometer cannot be used directly as an ammeter in a circuit for the following two reasons:
$(i)$ $A$ galvanometer is a very sensitive device; it gives a full-scale deflection for a current of the order of $\mu A$. Connecting it directly to a circuit with a higher current would damage the coil.
$(ii)$ To measure current,an ammeter must be connected in series. Since a galvanometer has a relatively large resistance,connecting it in series would significantly change the value of the current in the circuit.
Original current: $I = \frac{V}{R}$
After connecting the galvanometer (resistance $G$): $I' = \frac{V}{R + G}$
Additionally,if a galvanometer is used to measure a large current,the thin copper wire of the galvanometer coil is likely to burn due to the large amount of heat produced,according to the formula $H = I^2Rt$.