Question

A galvanometer having a coil resistance of $100 \, \Omega$ gives a full scale deflection, when a current of $1 \,mA$ is passed through it. The value of the resistance, which can convert this galvanometer into ammeter giving a full scale deflection for a current of $10\, A$ is :

• A. $0.01\, \Omega$
• B. $2 \,\Omega$
• C. $0.1 \,\Omega$
• D. $3\,\Omega$

Answer 1

Answer: (A)

$0.01\, \Omega$

Answer 2

Maximum voltage that can be applied across the galvanometer coil $= 100 \, \Omega \times 10^{-3} A = 0.1 \, V.$
If $R_s$ is the shunt resistance :
$R_S \times 10 A = 0.1 V$
$\Rightarrow \, R_S = 0.01 \Omega$