MHT CET · Physics · Current Electricity

The range of an ammeter of resistance ‘G’ can be increased from ‘I’ to ‘nI’ by connecting

A A series resistance of $\frac{G}{n + 1} Ω$
B A shunt of $\frac{G}{n - 1} Ω$
C A shunt of $\frac{G}{n + 1} Ω$
D A series resistance of $\frac{G}{n - 1} Ω$

Verified Solution

Answer & Solution

Correct Answer

(B) A shunt of $\frac{G}{n - 1} Ω$

Step-by-step Solution

Detailed explanation

The range of an ammeter can be increased by connecting a shunt or parallel resistance to it, whose value is given by

R = (\frac{l_{g}}{l - l_{g}}) G Ω

To increase the range from l to

n l,

the current passing through it is l =

n l_{g}

Using this value in Eq. (i), we get

R = (\frac{l_{g}}{n l_{g} - l_{g}}) G

= \frac{G}{(n - 1)} Ω

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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