What damping is used in PMMC instrument?

Correct option is A

· Eddy current damping is used where a high value of the magnetic field is required.
· For instance, eddy current damping is generally used in Permanent Magnetic Moving Coil which is known as PMMC and it is an instrument which is used to measure current or voltage.

$$\begin{array}{|c|l|}\hline\textbf{Type of damping} & \textbf{Instruments used} \\\hline\text{Air friction damping} & \text{Moving iron (MI) and EDM (Electro dynamometer) instruments} \\\hline\text{Fluid friction damping} & \text{Electro-static voltmeter (ESV) and Induction type instruments} \\\hline\textbf{Eddy current damping} & \textbf{PMMC and induction type (which are used permanent magnet)} \\\hline\text{Electromagnet damping} & \text{Flux meter} \\\hline\end{array}$$​