Question

A voltmeter of resistance 1000$\Omega$ gives full scale deflection when a current of 100 mA flow through it. The shunt resistance required across it to enable it to be used as an ammeter reading 1 A at full scale deflection is

• A. $10000\Omega$
• B. $9000\Omega$
• C. $222\Omega$
• D. $111\Omega$

Answer 1

Answer: (D)

$111\Omega$

we know that for voltmeter :

$\frac{i}{i_g}=1+\frac{G}{S}$

According to question:

$\Rightarrow \frac{i}{100\times {10}^{-3}}=1+\frac{1000}{S}\Rightarrow S=\frac{1000}{9}=111\Omega$