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 :

Options

A. `1A`
B. 0.5A
C. 0.25A
D. 2A

Answer

B

Explanation

Equivalent resistance,

`R.=R+(R_(A)xxS)/(R_(A)+S)`
= `40.8+(480xx20)/(480+20)`
= `40.8+19.2=60.0Omega`
`therefore` Current in the circuit,
`I=V/(R.)=30/60=0.5A`
`therefore` Measurement of ammeter is 0.5A.