Question

A circuit contains an ammeter, a battery of 30V and a resistance 40.8Ω all connected in series. If the ammeter has a coil of resistance 480Ω and a shunt of 20Ω, the reading in the ammeter will be: (a) 0.25 A(b) 2A(c) 1 A(d) 0.5 A

Answer 1

the answer is (d) 0.5A

Answer 2

Answer:

(d) 0.5 A

Explanation:

In this question

We have been given that

A battery of 30 V and a resistance 40.8Ω all connected in series. If the ammeter has a coil of resistance 480Ω and a shunt of 20Ω,

Effective resistance of a circuit show in figure

$R_eff$ = $40.8 + \frac{480\times 20}{480 + 20}$

                        = 40.8 + 19.2

                        = 60Ω  

So, current flowing across ammeter,

$I$ = $\frac{V}{R}$

                = $\frac{30}{60}$

                = $\frac{1}{2}$

                = 0.5 A

Hence, reading of ammeter = 0.5 A