Final answer:
Correct answer is (a) Resistance increases.The resistance of a copper wire increases as temperature rises from 20 degrees Celsius because the increase in atomic vibrations causes more frequent electron collisions.
Step-by-step explanation:
When the temperature of a copper wire increases from 20 degrees Celsius, the resistance of the wire increases. This is due to the temperature dependence of the material's resistivity. As copper’s temperature rises, the atoms within the wire vibrate more, which means electrons moving through the wire collide more frequently, increasing the wire's resistivity. Therefore, a rise in temperature causes an increase in resistance for copper wire.
The resistance of a copper wire at 20 degrees Celsius is 5 ohms. When the temperature increases, the resistance of the wire will increase. This is because the resistivity of copper (the measure of how much a material resists the flow of electric current increases with temperature.