Question

The value of current obtained in a moving coil galvanometer is proportional to:

• A. deflection (\(\theta\))
• B. resistance (\(R\))
• C. magnetic field (\(B\))
• D. none of those

Hint:

Current in moving coil galvanometer: \[ I = k \theta, \] where \( k \) is a constant depending on the galvanometer’s construction.

Answer 1

The Correct Option is A

In a moving coil galvanometer, the deflection \( \theta \) of the coil is directly proportional to the current \( I \) passing through it. This is because the torque experienced by the coil due to the magnetic field is proportional to the current, and the restoring torque of the suspension wire balances it at equilibrium. Mathematically, this relationship can be expressed as: \[ I \propto \theta, \] or equivalently, \[ I = k \theta, \] where \( k \) is a constant of proportionality dependent on the galvanometer's construction. This linear relationship allows the galvanometer to measure current by observing the angular deflection of its coil.