Question

The resistance coils in a resistance box are made of double folded wire so that their
A. Self induction is nullified
B. Self induction is maximum
C. Induced emf is maximum
D. None of these

Answer 1

Hint: In order to deal with this question we will study what a resistance box is and what it comprises. Further we will see the reason behind the use of double folded wire in the resistance box and what is the benefit of using that.

Complete step-by-step answer:

The package that holds the resistors with various values for resistance estimation and comparison is known as the resistor box.
Presence of inductance increases the impedance more than the actual resistance value. Therefore to reduce the chance of occurrence of inductance in the resistor coils, they are double folded, so that current in opposite directions cancel the induced flux linkages if any and hence inductance is nullified.
Hence, the resistance coils in a resistance box are made of double folded wire so that their Self induction is nullified.
So, the correct answer is option A.

Additional information: An object's electrical resistance is a function of its response to the electric current wave. The inverse amount is electrical conductance, and is the ease with which an electrical current passes through. The idea of mechanical friction has certain philosophical similarities with electrical resistance. The electrical resistance unit SI is the ohm, while the electrical conductance is measured in siemens.

Note: The accuracy of the resistance box is very high. The main application of the resistance box is to control the current specified value to flow through the circuit. Sometimes rheostat can also be used in the place of a resistance box, but the difference is that rheostat has variable resistance along its length but the rheostat has discrete resistance and the values are fixed. Mostly resistance box is used in experiments and practical.