question_answer

In an ammeter 0.2% of main current passes through the galvanometer. If resistance of galvanometer is G, the resistance of ammeter will be                                                                                                              [NEET 2014]

A)  \[\frac{1}{499}G\]       

B)       \[\frac{499}{500}G\]    

C)  \[\frac{1}{500}G\]       

D)       \[\frac{500}{499}G\]

Correct Answer: A

Solution :

[a] For ammeter

\[0.0002l\times G=0.998l\times {{r}_{g}}\]

\[{{r}_{g}}=\frac{0.002}{0.998}G\]

\[\Rightarrow \]   \[{{r}_{g}}=0.002004G=\frac{1}{499}\times G\]

Resistance of ammeter is approximately equal to resistance of shunts.