What is Tangent Galvanometer?
A tangent galvanometer is a scientific instrument used to measure small electric currents. It works based on the principle of the tangent law, which relates the angle of deflection of a magnetic needle to the strength of an electric current passing through a coil of wire. Tangent galvanometers were commonly used in the 19th and early 20th centuries for educational and experimental purposes.
Key features and components of a tangent galvanometer include:
- Circular Coil of Wire: The instrument consists of a circular coil of wire, often wound around a non-magnetic frame or bobbin. The coil is placed horizontally and can rotate around a vertical axis.
- Magnetic Needle: A small magnetic needle is suspended at the center of the coil. The needle is free to rotate and aligns itself with the Earth’s magnetic field.
- Scale: A circular scale is placed around the coil, allowing the angle of deflection of the magnetic needle to be measured.
- Current Source: An electric current is passed through the coil using a battery or other current source.
When an electric current flows through the coil, it generates a magnetic field around the coil. This magnetic field interacts with the Earth’s magnetic field, causing the magnetic needle to deflect from its original orientation. The angle of deflection (θ) is measured on the circular scale. The tangent of the angle of deflection is proportional to the ratio of the current (I) passing through the coil to the horizontal component of the Earth’s magnetic field (H). Mathematically, this relationship can be expressed as:
tan(θ) = (k * I) / H
Where:
θ = Angle of deflection of the magnetic needle
I = Electric current passing through the coil
H = Horizontal component of the Earth’s magnetic field
k = A constant that depends on the specific design of the galvanometer
Tangent galvanometers were used to measure small currents and were popular for educational purposes. However, they have been largely replaced by more accurate and versatile current measurement devices, such as digital multimeters and ammeters, in modern times. Nonetheless, the tangent galvanometer holds historical significance as an early instrument used to study the relationship between electric currents and magnetic fields.