A cylindrical metal wire at room temperature is carrying electric current betwee

Question

A cylindrical metal wire at room temperature is carrying electric current between its ends. One end is at potential VA = 50 V, and the other end is at potential VB = 0 V. Rank the following actions in terms of the change that each one separately would produce in the current from the greatest increase to the greatest decrease. In your ranking, note any cases of equality. (Use only ">" or "=" symbols. Do not include any parentheses around the letters or symbols.)

(a) Make VA = 150 V with VB = 0 V.

(b) Adjust VA to triple the power with which the wire converts electrically transmitted energy into internal energy.

(c) Double the radius of the wire.

(d) Double the length of the wire.

(e) Double the Celsius temperature of the wire.

Explanation / Answer

(c) Double the radius of the wire. [? ? 4?]
assuming a solid cylinder, or hollow cylinder with constant thickness
and temperature remains constant, otherwise current specified is only approximate, but may be slightly higher or lower, dependent upon thermal conductivities, and temperature coefficient of resistance

(a) Make VA = 150 V with VB = 0 V. [ ? ? 3?]
assuming temperature remains constant, otherwise slightly less than specified

(b) Adjust VA to triple the power with which the wire converts electrically transmitted energy into internal energy. [? ? ?3?]
assuming temperature remains constant otherwise, slightly less than specified

(e) Double the Celsius temperature of the wire. [? ? ? 0.9?]
based on typical temperature coefficient of resistance for common conductors and a temperature increase of about 20?

(d) Double the length of the wire. [? ? 0.5?]

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