Resistors are put into electrical circuits to control the flow of current within the components of an electrical appliance. Sometimes a resistor with a particular value of resistance has to be made. For example, in order to give the right amount of heat, the heating element of a kettle must have just the right value of resistance. What are the factors that affect the resistance of a conducting wire? Students investigated how the length, diameter, or temperature of this wire affected its resistance to current when connected in circuit with a constant power source.