Question

Best method to increase the sensitivity of the moving coil galvanometer is to increase :

• A. radius of the coil
• B. number of turns of the coil
• C. external magnetic field
• D. none of the above

Answer 1

Answer: (C)

$\sigma =n\frac{AB}{c}$. Increase in n increases the resistance of the coil. Increase in A also increases length of each turn and hence resistance of the coil increases. Thus there is a limit upto which n or A can be increased. Also, the value of torsional torque per unit twist (c) depends on the nature of material of the suspension wire. Thus, the best way to increase $\sigma$ is to increase B.