A galvanometer gives full scale deflection of 1 volt when acting like a volmeter when connected in series with `2 kOmega` resistance. The same galvanometer gives `500 mA`, full scale deflection when acting like a ammeter when connected with shunt resistance of value `0.2 Omega` in parallel. Find out the resistance of galvanometer.

Options

A. `108Omega`
B. `222Omega`
C. `250Omega`
D. `1.5 kOmega`

Answer

B

Explanation

`V=I_(g)(R+G)`
`1=I_(g)(2000+G)impliesI_(g)=1/(2000+G) …(1)`

`I_(g)G=(0.5-I_(g))xx0.2`
`I_(g)G=0.1-0.2I_(g)`
`I_(g)(G+0.2)=0.1 …(2)`
From (1) and (2)
`(1/(2000+G))(G+0.2)=0.1`
`G+0.2=200+0.1G`
`0.9G=199.8`
`G=199.8//0.9 Omega=222 Omega`