Question

Tangent galvanometer is used to measure

• A. potential difference
• B. current
• C. resistance
• D. charge

Answer 1

The Correct Option is B

The tangent galvanometer is a scientific instrument used to measure current. Understanding how this device works is key to determining why the correct answer is 'current' and not the other options provided.

The tangent galvanometer operates on the principle of the tangent law in magnetism. When a current passes through a coil of wire, it creates a magnetic field. The device consists of a coil, a compass needle at the center, and a scale to measure angles.

• When the coil is aligned in the north-south direction, the earth's magnetic field deflects the compass needle. The coil’s magnetic field due to the current passing through it causes further deflection.
• The deflection angle \(\theta\) of the needle is related to the current \(I\) flowing through the coil.
• The tangent law for the device can be mathematically expressed as: I = \frac{K}{B_H} \tan(\theta), where \(K\) is the instrument constant and \(B_H\) is the horizontal component of the earth's magnetic field.

The measurement process highlights why a tangent galvanometer specifically measures current and not other electrical quantities like potential difference, resistance, or charge:

• Potential difference: Measured by a voltmeter, it represents energy per unit charge and isn't directly related to magnetic fields.
• Resistance: Determined using an ohmmeter, it's the opposition to the flow of electric current.
• Charge: Usually calculated using the quantity of current and time, but not directly measured by the tangent galvanometer.

Thus, the tangent galvanometer is used to measure current, as it leverages the magnetic effects produced by current flow in a coil.