Question

how to make working model on topic : To study the earth magnetic field using tangent galvanometer?

Answer 1

A tangent galvanometer is an early measuring instrumentused for the measurement ofelectric current. It works by using a compass needle to compare amagnetic field generated by the unknown current to the magnetic field of the Earth. It gets its name from its operating principle,the tangent law of magnetism, which states that the tangent of the angle a compass needle makesis proportional to the ratio of the strengths of the two perpendicular magnetic fields. It was first described by Claude Pouilletin 1837.A tangent galvanometer consists of a coil of insulated copper wire wound on a circular non-magneticframe. The frame is mounted vertically on a horizontal base provided with levelling 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 aluminium pointer is attachedto the needle at its centre and at right angle to it. To avoid errors due to parallax a plane mirror is mounted below the compass needle.