(a) Briefly explain how a galvanometer is converted into an ammeter.
(b) A galvanometer coil has a resistance of `15 Omega` and it shows full scale deflection for a current of 4 mA. Convert it into an ammeter of range 0 to 6 A.

Explanation

### Solution:

**(a)** To convert a galvanometer into an ammeter, we need to connect a shunt resistor in parallel with the galvanometer. The shunt resistor allows most of the current to bypass the galvanometer, ensuring that only a small fraction of the total current flows through it. This is necessary because the galvanometer is designed to measure small currents, and without the shunt, it would be damaged by larger currents. The value of the shunt resistor is calculated based on the full-scale deflection current of the galvanometer and the desired range of the ammeter.

**(b)** Given:
- Resistance of galvanometer (Rg) = 15 Ω
- Full-scale deflection current (Ig) = 4 mA = 0.004 A
- Desired range of ammeter (Ia) = 6 A
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