Q109 / 150 · MHT CET 2026 (13 April Shift 1) · Physics
If the number of turns in the coil of a moving coil galvanometer decreases, the resistance of the galvanometer,
- Correct answerAdecreases
- Bincreases
- Cremains the same
- Dmay increase or decrease
Solution
The resistance of a coil is given by $R = \rho \dfrac{l}{A}$.
The total length of the wire in the coil is $l = N \times \text{perimeter of one turn}$, where $N$ is the number of turns.
Thus, the resistance of the galvanometer is directly proportional to the number of turns ($R \propto N$).
When the number of turns in the coil decreases, the total length of the wire decreases.
Consequently, the resistance of the galvanometer decreases.
Answer: decreases
The total length of the wire in the coil is $l = N \times \text{perimeter of one turn}$, where $N$ is the number of turns.
Thus, the resistance of the galvanometer is directly proportional to the number of turns ($R \propto N$).
When the number of turns in the coil decreases, the total length of the wire decreases.
Consequently, the resistance of the galvanometer decreases.
Answer: decreases
Hence, the correct answer is option: 'A'.