G2 Gas Fitter Practice Exam

What phenomenon increases in a wire as temperature rises due to electrical current?

1. Voltage

2. Magnetism

3. Resistance

4. Conductivity

The correct answer is: Resistance

As the temperature of a wire increases due to the flow of electrical current, the resistance of the wire also increases. This phenomenon occurs because the atoms within the wire vibrate more vigorously at higher temperatures, which leads to more frequent collisions between the flowing electrons and the vibrating atoms. These collisions hinder the free movement of electrons, thereby increasing resistance. Resistance is a crucial concept in understanding how electrical circuits operate because it determines how much current will flow for a given voltage. The higher the resistance, the less current will flow under a set voltage, which is described by Ohm's Law. In contrast, as temperature increases, magnetism and voltage do not inherently increase as a direct result of the temperature rise; instead, they are affected by other factors. Similarly, conductivity, which refers to a material's ability to conduct electric current, typically decreases with an increase in temperature for metals, contradicting the behavior of resistance. This highlights why an increase in temperature in a material like copper leads to a corresponding increase in resistance rather than a change in conductivity or voltage directly.