# GIVE THE DETAILED DESCRIPTION ABOUT TANGENT GALVANOMETER
sir/mam
i dont know anything about it ,
please... along with definition ,add some more points that can add up my marks..

### Asked by preethambasilmartis | 21st Jun, 2016, 04:26: PM

Expert Answer:

### In order to understand working mechanism of Tangent Galvanometer, the knowledge of **Tangent law of Magnetism** is essential.
**Tangent law of Magnetism** :-
- The tangent law of magnetism states that the tangent of the angle of a compass needle which is due to the movement under the influence of magnetic field is directly proportional to the ratio of
**strengths** of two perpendicular magnetic fields.
- In simpler words, the tangent of the angle made by the moving needle under the magnetic field directly indicates the strength of the perpendicular magnetic fields.

**Tangent Galvanometer**:-
** Definition**
- Tangent galvanometer is the device which was used to measure small amounts of electric current.

** Construction**
- The working of tangent galvanometer is based on the principle of tangent law of magnetism.
- It consists of a coil of insulated copper wire wound on a circular non-magnetic frame.
- It is utmost necessary that the coil wound is done in helical arrangement otherwise, the field due to the wire will affect the compass needle, thus inducing an error in the reading.
- This frame is mounted vertically on a horizontal base for support.

- The coil of insulated copper wire is usually rotated on a vertical axis passing through its centre.

- A small sized magnetic compass with a powerful magnetic needle is made to pivote at the centre of this coil, such that it is free to rotate in a horizontal plane.

- The circular scale is used to read the movement of this magnetic needle which is divided into four quadrants, each ranging from 0° to 90°.

- A pointer is attached to this needle at right angles, usually made up of thin alluminium as alluminium is lighter in mass.
- The usual way of discarding possibilities of parallax is also used i.e placing of a plane mirror below the compass needle.

** **
** Working**
- The instrument needle starts moving firstly under the influence of Earth's magnetic field.
- Movement continues untill the magnetic field of earth is parallel with the plane of coil.
- Then, on application of an uknown current, a second magnetic field on the axis of the coil which is perpendicular to the Earth's magnetic field is created.
- Hence the compass needle responds to the vector sum of the two fields.
- This deflection angle is equal to the tangent of the ratio of those two fields.

**Tangent law of Magnetism**is essential.

**Tangent law of Magnetism**:-

- The tangent law of magnetism states that the tangent of the angle of a compass needle which is due to the movement under the influence of magnetic field is directly proportional to the ratio of
**strengths**of two perpendicular magnetic fields. - In simpler words, the tangent of the angle made by the moving needle under the magnetic field directly indicates the strength of the perpendicular magnetic fields.

**Tangent Galvanometer**:-

**Definition**

- Tangent galvanometer is the device which was used to measure small amounts of electric current.

**Construction**

- The working of tangent galvanometer is based on the principle of tangent law of magnetism.
- It consists of a coil of insulated copper wire wound on a circular non-magnetic frame.
- It is utmost necessary that the coil wound is done in helical arrangement otherwise, the field due to the wire will affect the compass needle, thus inducing an error in the reading.
- This frame is mounted vertically on a horizontal base for support.
- The coil of insulated copper wire is usually rotated on a vertical axis passing through its centre.
- A small sized magnetic compass with a powerful magnetic needle is made to pivote at the centre of this coil, such that it is free to rotate in a horizontal plane.
- The circular scale is used to read the movement of this magnetic needle which is divided into four quadrants, each ranging from 0° to 90°.
- A pointer is attached to this needle at right angles, usually made up of thin alluminium as alluminium is lighter in mass.
- The usual way of discarding possibilities of parallax is also used i.e placing of a plane mirror below the compass needle.

**Working**

- The instrument needle starts moving firstly under the influence of Earth's magnetic field.
- Movement continues untill the magnetic field of earth is parallel with the plane of coil.
- Then, on application of an uknown current, a second magnetic field on the axis of the coil which is perpendicular to the Earth's magnetic field is created.
- Hence the compass needle responds to the vector sum of the two fields.
- This deflection angle is equal to the tangent of the ratio of those two fields.

### Answered by Abhijeet Mishra | 29th Nov, 2017, 03:25: PM

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