Question

If the current is doubled, the deflection is also doubled in
A. a tangent galvanometer
B. a moving-coil galvanometer
C. both
D. none of these

Answer 1

Hint: Recall the equation for the moving coil galvanometer's angular deflection. Then observe the relationship between the specified quantities and the moving coil galvanometer's angular deflection. Check to see if the amounts are directly or inversely proportional to angular deflection. An electromagnetic tool used to measure tiny electric currents is a moving coil galvanometer. The galvanometer is made up of a coil with several turns that can freely revolve around a fixed axis.

Complete step by step solution:
It is known that, number of turns in the coil is directly proportional to angular deflection. A moving coil galvanometer’s current and deflection dependence is given by
\[i = \dfrac{k}{{nAB}}\theta \]
Where:
The current flowing is denoted by \[I\]
The number of turns in the coil is \[N\]
The area of the coil is \[A\]
The magnetic field is \[B\]
The torsional constant\[K\]

The above relation can also be written as,
\[ \Rightarrow i \propto \theta \]
Therefore, the deflection also gets doubled, if we double the current.
However, in a tangent galvanometer
\[i \propto \tan \theta \];
That is, between \[\theta \] and current there is no direct relation.

Hence, option B is correct.

Note: Most of the students tend to make mistakes while writing the formula. This current-carrying coil experiences a torque and rotates about the fixed axis when current runs through it and the gadget is put in a uniform magnetic field. The existence and deflection of current are indicated by this deflection.