(N/A) In a laboratory,two types of resistors are commonly used:
$(1)$ Wire-wound resistors
$(2)$ Carbon resistors
$(1)$ Wire-wound resistors:
- These resistors are prepared by winding alloys like manganin,constantan,or nichrome on a suitable base.
- The resistivity of these materials does not vary significantly with temperature.
- They have a high current-carrying capacity.
- They are typically used in laboratory settings for precision and high-power applications.
$(2)$ Carbon resistors:
- Carbon resistors are prepared using a mixture of graphite and a resin binder.
- At high temperature and pressure,they are molded into a cylindrical shape.
- Conducting wires are connected to both ends of the cylinder.
- $A$ protective coating of ceramic or plastic is applied over the cylindrical arrangement.
- Carbon resistors have resistance values ranging from $1 \Omega$ to $100 \text{ M}\Omega$.
- Carbon resistors are compact,inexpensive,and thus find extensive use in electronic circuits.