Question
The ammeter shown in figure consists of a 480 Ω coil connected in parallel to a 20 Ω shunt. The reading of ammeter is
0.125 A
1.67 A
0.13 A
0.67 A
Solution
A.
0.125 A
Given:- The ammeter coil of resistance 480Ω and shunt of to a 20Ω are connected in parallel
The equivalent resistance of the ammeter is
R' =
R' = 19.2 Ω
Now, resistance of 140.8 Ω and 19.2 Ω are in series, hence total resistance in the circuit,
The equivalent resistance of the circuit is
R = 140.8 Ω + 19.2 Ω = 160 Ω
The current I =
=
I = 0.125 A
Hence, ammeter reading is 0.125 A.
