Final answer:
The resistance of a conductor typically increases when its temperature rises or when it is physically altered, such as being stretched to a longer length. The resistance quadruples if the wire is stretched to four times its original length due to proportional relation with length.
Step-by-step explanation:
Factors Causing Increase in Resistance
Normally, the resistance of a conductor will increase when either the temperature of the conductor rises or when its physical dimensions change. In the case of a wire being stretched to four times its original length, the resistance would increase by the same factor; meaning it would quadruple. This is because if you increase the length of a resistor by a certain factor, you will increase the resistance by the same factor.
Regarding temperature, as the temperature of a conductor increases, the atoms within it vibrate more intensely. This vibration causes more frequent collisions between the electrons and atoms, which in turn raises the resistance. This relationship is usually expressed by the equation R = R0(1 + αΔT), where α is the temperature coefficient and ΔT is the change in temperature.