IMAT 2012 Q73 [Conduction]

When cooled below 4.2 K, mercury becomes a superconductor, which means it has no electrical resistance. When a current is passed through mercury under these conditions, which of the following effects will be present?

  1. thermal
  2. chemical
  3. magnetic

A. 1 and 3 only
B. 1, 2 and 3
C. 2 only
D. 3 only
E. 1 only

Let’s look at each situation:

In the case that there is no electrical resistance, we can conclude that no thermal energy can be released- therefore we can say there will also be no thermal effect.

Since Mercury is a single element acting as the conductor, we also can conclude there can be no possible chemical effect.

Although, since Mercury is a metal, and there is electricity or current passed through it- we know that if there is electricity and a metal, there will surely be magnetism. Therefore, 3 is the only correct choice and our answer is D.