question_answer

A galvanometer has a coil resistance of 100 \[\Omega \] 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 :

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