An object is hung using a metal spring. If now a current is passed through the spring, what will happen to this system?
A) The spring will extend, lowering the weight.
B) The spring will begin to swing like a pendulum.
C) The spring will contract, raising the weight.
D) The weight will not move.
E) None of these are true.

Question

Quizplus · Accepted Answer

When a current passes through a metal spring, it generates heat due to the resistance of the metal. This heat causes the metal to expand slightly. However, in the context of a spring under tension from a hanging weight, the dominant effect is that the spring's material, while expanding, also loses some of its yield strength temporarily. This can cause the spring to contract slightly under the constant force from the weight, as the material's ability to resist deformation decreases. Thus, the weight is raised slightly. However, this explanation simplifies complex interactions, including potential thermal expansion. In many practical scenarios, the effect might be negligible or countered by the material's properties. The correct answer is chosen based on the options provided and the typical interpretation of the effects of heating a metal spring under tension.

An Object Is Hung Using a Metal Spring