Question

A tangent galvanometer measures current.
A) True
B) False

Answer 1

Hint: Tangent galvanometer is an instrument to measure small electric current. It works on the tangent law of magnetism. The current can be measured by deflect angle is equal to the tangent ratio of the vector sum of two fields.

Complete step by step answer:
A tangent galvanometer is a device used to measure electric current. It works by comparing an unknown current with the magnetic field of the Earth by using a compass needle. It is named after its working principle i.e. the tangent law of magnetism, according to which, the tangent of the angle a compass needle makes is proportional to the ratio of the strengths of the two perpendicular magnetic fields.

$\therefore $We can say that a tangent galvanometer measures current. Hence, Option (A) is correct.

Additional information:
- A tangent galvanometer consists of a coil of insulated copper wire wound on a circular non-magnetic frame. The frame is mounted vertically on a horizontal base with leveling screws. The coil can be rotated on a vertical axis passing through its centre. A compass box is mounted horizontally at the centre of a circular scale. It consists of a tiny, powerful magnetic needle pivoted at the centre of the coil. The magnetic needle is free to rotate in the horizontal plane.
- The circular scale is divided into four quadrants. Each quadrant is graduated from 0° to 90°. A long thin aluminum pointer is attached to the needle at its centre and at right angle to it.

Note:
During its operation the instrument is first rotated until the magnetic field of the Earth is parallel with the plane of the coil. Once both are parallel to each other, then only the unknown current is applied to the coil. This creates a second magnetic field on the axis of the coil, which is perpendicular to the magnetic field of earth.
The compass needle responds to the vector sum of the two fields, and deflects to an angle equal to the tangent of the ratio of the two fields. From the reading of the angle from the compass scale, the current can be calculated.