Two moving coil meters, `M_(1)` and `M_(2)` have following particulars`:`
`R_(1)=10Omega,N_(1)=30,A_(1)`
`=3.6xx10^(-3)m^(2),B_(1)=0.25T`
`R_(2)=10Omega,N_(2)=42,A_(2)`
`=1.8xx10^(-3)m^(2),B_(2)=0.50T`
`(` The spring constants are identical for two meters `)`. The ration of `(i)` current sensitivity `(ii)` voltage sensitivity of `M_(2)` and `M_(1)` is

Options

A. `1.4,1`
B. `1,1.4`
C. `1:1`
D. `1:4`

Answer

C

Explanation

Current sensitivity of a moving coil galvanometer is defined as
`C.S.=(phi)/(I)=(NAB)/(k)`
and voltage sensitivity, `V.S. =(NAB)/(kR)`
`(i)` Ratio of current sensitivity
`(C.S_(2))/(C.S_(1))=(N_(2)B_(2)A_(2)k)/(N_(1)B_(1)A_(1)k)=(42xx1.8xx0.5xx10^(-3)xxk)/(30xx0.25xx03.6xx10^(-3)xxk)=1.4`