Question

A circuit contains an ammeter, a battery of $30V$ and a resistance $40.8$ ohm all connected in series. If the ammeter has a coil of resistance $480$ ohm and as shunt of $20$ ohm, the reading in the ammeter will be:

• A. $1A$
• B. $0.5A$
• C. $0.25A$
• D. $2A$

Answer 1

The correct option is B $0.5A$

Resistance of ammeter: $r_{am}=\frac{480\times 20}{480+20}=19.2$
Current : $i=\frac{30}{40.8+19.2}=0.5amp$