Question

In a tangent galvanometer, when a current of `10mA` is passed, the deflection is `31^@`. By what percentage, the current has to be increased, so at to produce a deflection of `42^@`?

Answer 1

Here, `I_1=10mA, theta_1=31^@`,
`I_2=? theta_2=42^@`
As `I_2/I_1=(tan theta_2)/(tan theta_1)`
`:. I_2=I_1(tan theta_2)/(tan theta_1)=10xx(tan 42^@)/(tan theta_31^@)=(10xx0*9)/(0*6)`
`=15mA`.
Percentage Increase in current
`((I_2-I_1))/(I_1)xx100=((15-10))/(10)xx100=50%`