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Question:

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

1 A

0.25 A

0.5 A

2 A

Solution:

Resistance of ammeter: Ram = (480 × 20) / (480 + 20) = 19.2 Ω
Current: i = 30 / (40.8 + 19.2) = 0.5 A