# To know the resistance G of a galvanometer by half deflection method, a battery of emf VE and resistance R is used to deflect the galvanometer by angle   θ.  If a shunt of resistance S is needed to get half deflection then G, R and S are related by the equation : Option 1) 2S  (R + G) = RG Option 2) S ( R + G) = RG Option 3) 2S = G Option 4)  2G = S

As we learnt in

Moving coil galvanometer -

It is a very sensitive instrument used to measure the small current.Galvanometer gives the deflection which is proportional to electric current flowing through it.

-

From Ohm's Law

where,  Ig = Galvanometer Current

G = Galvanometer resistance

When shunt of resistance s is connected parallel to the galvanometer then

After calculate, we get

RG = S(R+G)

Option 1)

2S  (R + G) = RG

This is incorrect option.

Option 2)

S ( R + G) = RG

This is correct option.

Option 3)

2S = G

This is incorrect option.

Option 4)

2G = S

This is incorrect option.

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