Question

Superconductors are substances which

• A. Offer no resistance to the flow of electricity
• B. Offer high resistance to the flow of current
• C. Conduct electricity at high temperatures
• D. Conduct electricity at low temperature

Hint:

Recall that below a critical temperature, superconductors show exactly zero electrical resistance.

Answer 1

The Correct Option is A

Compare a normal conductor and a superconductor as the temperature drops.

1. In an ordinary conductor such as copper, resistance decreases slowly as temperature falls, but some resistance always remains, however small.
2. In a superconductor, once the temperature drops below a specific critical value, the resistance does not just get small, it drops to exactly zero.
3. With zero resistance, a current loop set up in a superconducting ring keeps flowing without any driving voltage and without losing energy to heat.

This complete vanishing of resistance is the defining property that separates a superconductor from every other conductor, so option A is correct.

Option B describes high resistance, which is the opposite of what happens. Option C wrongly links the effect to high temperature, while superconductivity is a low temperature phenomenon. Option D only mentions conducting at low temperature, which any ordinary metal also does to some extent, and it misses the key point that resistance must become exactly zero, so it does not correctly define a superconductor.