question_answer

A galvanometer has a coil resistance of 100 Q. It gives a full scale deflection when a current of 1mA is passed through it. The value of resistance which can convert the galvanometer into an ammeter giving full scale deflection for a current of 10 A is

A)   \[{{10}^{-4}}\,\Omega \]

B)  \[{{10}^{-2}}\,\Omega \]

C)  \[{{10}^{4}}\,\Omega \]

D)  \[{{10}^{2}}\,\Omega \]

Correct Answer: B

Solution :

\[S=\frac{{{i}_{g}}G}{i-{{i}_{g}}}\] \[S=\frac{({{10}^{-3}}A)\,(100)}{(10-{{10}^{-3}})}=\frac{0.1}{9.99}\approx {{10}^{-2}}\,\Omega \]