Given below are two statements:
Statement I: If the number of turns in the coil of a moving-coil galvanometer is doubled, then the current sensitivity becomes double.
Statement II: Increasing current sensitivity of a moving-coil galvanometer only by increasing the number of turns in the coil will also increase its voltage sensitivity in the same ratio. Choose the correct answer.

Question

Given below are two statements:

Statement I: If the number of turns in the coil of a moving-coil galvanometer is doubled, then the current sensitivity becomes double.

Statement II: Increasing current sensitivity of a moving-coil galvanometer only by increasing the number of turns in the coil will also increase its voltage sensitivity in the same ratio. Choose the correct answer.

G1 Physics · Accepted Answer

Current sensitivity of a moving-coil galvanometer is θ/I = NBA/k So current sensitivity is directly proportional to the number of turns N. If N is doubled, current sensitivity doubles. Statement I is true. Voltage sensitivity is θ/V = NBA/(kR) When the number of turns is increased using the same wire, the coil resistance R also increases approximately in the same ratio. Therefore N/R remains nearly unchanged and voltage sensitivity does not double. Hence Statement I is true but Statement II is…