Question

An ammeter gives full deflection when a current of $2A$ flows through it. The resistance of ammeter is $12\Omega$. If the same ammeter is to be used for measuring a maximum current of $5A$, then the ammeter must be connected with a resistance of

• A. $8\Omega$ in series
• B. $18\Omega$ in series
• C. $8\Omega$ in parallel
• D. $18\Omega$ in parallel

Answer 1

The correct option is C $8\Omega$ in parallel

According to the question;

$\frac{I}{I_g}=1+\frac{G}{S}$

$\Rightarrow$ $\frac{5}{2}=1+\frac{12}{S}$

$\Rightarrow$ $S=8\Omega$ (in parallel)