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A galvanometer of resistance 20 ohm gives full scale deflection

Answer»

Dear STUDENT,

# Complete question should be -

Q. A GALVANOMETER of resistance 20 ohm gives a full scale deflection when a current of 0.04A is passed through it. It is desired to convert it into an ammeter of full scale reading 20A. The only shunt availaible is 0.05 ohm resistance. The resistance that must be connected in series with the coil of galvanometer is?

◆ Answer -

X = 4.95 ohm

◆ Explanation -

# Given -

G = 20 ohm

S = 0.05 ohm

Ig = 0.04 A

I = 20 A

# Solution -

For galvanometer to be work as ammeter, its resistance should be -

G' = S(I-Ig)/Ig

G' = 0.05 × (20-0.04) / 0.04

G' = 5/4 × 19.96

G' = 24.95 ohm

Let X be extra resistance that must be added to series with galvanometer coil.

G' = G + X

X = G' - G

X = 24.95 - 20

X = 4.95 ohm

Therefore, resistance of 4.95 ohm is added to series with galvanometer coil.

Thanks dear...


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