A resistance of 900 Ω is connected in series with a galvanometer of resistance 100 Ω. A potential difference of 1 V produces . . .

Question : A resistance of 900 Ω is connected in series with a galvanometer of resistance 100 Ω. A potential difference of 1 V produces 100 division deflections in the galvanometer. Find the figure of merit of the galvanometer?

a) 10-6 A/div
b) 2×10-5 A/div
c) 10-5 A/div
d) 0.5×10-5 A/div

Doubt by Tanya 

Solution : 
R = 900Ω
G = 100 Ω
V = 1 V
θ= 100 div
Figure of Merit (G) = I/θ = k/NBA
We know,
V = I Req
V=I(R+G)
I=V/(R+G)
I=1/(900+100)
I=1/1000
I=10-3 A

Now,
G = I/θ
G=10-3/100
G=10-5 A/div
Hence, c) 10-5 A/div is correct.