Question 29: Current Electricity

Question

The wire made of Phosphor bronze is used as the suspension strip in the moving coil galvanometer, because:

Accepted Answer

The correct answer is Option D.
Ã¢ÂÂ¢ In a moving-coil galvanometer the coilÃ¢ÂÂs deflection ÃÂ¸ under current I is given by
$$NIA = k\,	heta$$
where $k$ is the torsional (restoring) constant of the suspension.
Ã¢ÂÂ¢ To get a large deflection for a small current, you want $k$ as small as possibleÃ¢ÂÂi.e. a small restoring torque per unit twist.
Ã¢ÂÂ¢ Phosphor bronze is chosen because it
has a low torsional constant (small $k$), boosting sensitivity
is elastic with very little hysteresis (so readings are stable and repeatable)
maintains good tensile strength and fatigue resistance over many cycles.
Hence its small restoring torque per unit twist makes phosphor bronze ideal as the suspension strip.

Answer

Its restoring torque per unit twist is very large

Answer

It is more flexible

Answer

It has less tensile strength

Answer

Its restoring torque per unit twist is small.

Current Electricity

The wire made of Phosphor bronze is used as the suspension strip in the moving coil galvanometer, because:

Choose the correct answer: