Question

the full scale deflection current for a galvanometer is 100 mA. how will you convert it to measure a voltage of 100 volts if it is able to measure a voltage of 10 volt​

Answer 1

Answer:

Galvanometer is a very sensitive instrument therefore it cannot measure heavy currents. In order to convert a Galvanometer into an Ammeter, a very low shunt resistance is connected in parallel to Galvanometer. Value of shunt is so adjusted that most of the current passes through the shunt.

If resistance of galvanometer is R

g

and it gives full-scale deflection when current I

g

is passed through it. Then,

V=I

g

R

g

V=100mA×100Ω

Let a shunt of resistance (R

s

) is connected in parallel to galvanometer. If total current through the circuit is I.

I=10A=I

s

+I

g

V=I

s

R

s

=(I−I

g

)R

s

(I−I

g

)R

s

=I

g

R

g

(10−10

−3

)R

s

=100×10

−3

R

s

=11.11Ω