A galvanometer has a current sensitivity of 5 div/m A and a voltage sensitivity of 2 div/m V . If the instrument has 30 divisions. How will you use it
A galvanometer has a current sensitivity of 5 div/m A and a voltage sensitivity of 2 div/m V . If the instrument has 30 divisions. How will you use it to measure a current of 3A?
A. `0.001Omega`
B. `0.005Omega`
C. `0.002Omega`
D. `0.004Omega`
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Correct Answer - B
(i) `S_V=(S_i)/(G) G=(S_i)/(S_V)=(5)/(2)=2.5Omega`.
(ii) For 1m A , the deflection is 5 divisions. Thus , for 30 divisions , i.e., current requried for maximum deflection is 6 m A , i.e., `I_g`. Therefore,
`S=((I_g)/(I-I_g))G=(6xx10^-3)/((3-0.006))xx2.5=5mOmega`.
`=0.005Omega`.
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