The coil of a galvanometer is `0*02xx0*8m^2`. It consists of `200` turns of the wire and is in a magnetic field of `0*20T`. The restoring torque constant of suspension fibre is `10^-6Nm//degree`. Assuming magnetic field to be radial (a) What is the maximum current that can be measured by this galvanometer if scale can accommodate `45^@`deflection? (b) What is the smallest current that can be detected if minimum observed deflection is `0*1 degree`?

Answer

(a) `4*69xx10^-4A` (b) `1*56xx10^-6A`

Explanation

Here, `A=0*02xx0*8m^2`, `n=200`,
`B=0*20T`, `k=10^-5Nm//degree`
(a) `I_(max.)=?`, `theta=45^@`, (b) `I_(min.)=?`, `theta=0.1^@`
Use the relation, `I=(k)/(nBA)theta`