Question

In majority of instruments damping is provided by:

• A. Fluid friction
• B. Spring
• C. Eddy currents
• D. Counter weights

Hint:

\textbf{Eddy current damping} is widely used in analog instruments because it is smooth, wear-free, and requires no physical contact.

Answer 1

The Correct Option is C

In measuring instruments, especially indicating-type instruments like analog ammeters and voltmeters, damping is essential to achieve a stable pointer reading without oscillations.
Eddy current damping is the most commonly used method. When a conductor moves in a magnetic field (or vice versa), eddy currents are induced in the conductor. These currents oppose the motion according to Lenz’s Law, thereby producing a damping torque.
This method is efficient, reliable, and maintenance-free, making it suitable for use in the majority of instruments.
Other methods like fluid friction damping and air friction damping are used in some cases but are less common due to complexity or bulkiness. Springs provide control torque, not damping. Counterweights are used for balancing, not damping.