Question

In rheostat what decides the resistance in the circuit?

• A. Area of the coiled wire in rheostat
• B. Resistivity of the coiled wire in rheostat
• C. Length of the coiled wire in rheostat
• D. Density of the coiled wire in rheostat

Answer 1

The correct option is C Length of the coiled wire in rheostat

A rheostat is a Resistance element with considerable length. It is usually metallic in nature. The defining equation is $R=\rho \frac{L}{A}$

Where;

$\rho$=resistivity of the element

$L$=length of the wire.

$A$= area of cross section of the wire.

The electrical component rheostat, have 3 terminals; Two terminals are the beginning and end of the wire, while the 3${}^{rd}$ terminal is the movable contact which can be moved along the length of the wire.

$\rho$ and $A$ remains the same throughout; thus the resistance between terminals is decided by the length of wire between them.