A tangent galvanometer is an instrument, developed in the...

Name: Problem 107, Chapter 19: Physics
Uploaded: 2021-07-21T17:42:47-08:00
Duration: 6 min 18 s
Channel: Vishal Gupta
Description: A tangent galvanometer is an instrument, developed in the nineteenth century, designed to measure current based on the deflection of a compass needle. A coil of wire in a vertical plane is aligned in the magnetic north-south direction. As illustrated, a compass is placed in a horizontal plane at the center of the coil. When no current flows, the compass needle points

A tangent galvanometer is an instrument, developed in the nineteenth century, designed to measure current based on the deflection of a compass needle. A coil of wire in a vertical plane is aligned in the magnetic north-south direction. As illustrated, a compass is placed in a horizontal plane at the center of the coil. When no current flows, the compass needle points

Key Concepts

Tangent Galvanometer

A tangent galvanometer is an instrument used to measure electrical current by employing the principle that the deflection of a compass needle is proportional to the tangent of the ratio between the magnetic field generated by a current-carrying coil and the Earth's magnetic field. This relationship, known as the tangent law, allows for the calculation of current magnitude based on the observed angular deviation.

Magnetic Fields from Electric Currents

Electric currents flowing through conductors induce magnetic fields around them. When these conductors are formed into a coil, the produced magnetic field becomes stronger and more uniform at the center, which is essential for creating measurable interactions with external magnetic fields in devices like the tangent galvanometer.

Earth's Magnetic Field

The Earth has a naturally occurring magnetic field, which generally aligns with the geographical north-south axis. This consistent magnetic directional field serves as a baseline in experiments and instruments, such as the tangent galvanometer, to compare with additional magnetic fields produced by currents.

Compass Needle Deflection and Tangent Law

The deflection of a compass needle occurs due to the vector addition of the Earth's magnetic field and another magnetic field induced by a current-carrying coil. The angle of deflection is related to the tangent of the ratio of these fields—a principle known as the tangent law—which allows one to quantitatively measure the current by observing the needle’s deviation.

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