Resistance Measurement and Heat


How does the the length of a wire affect its resistance? In testing this, what problems will arise from the heating effect of the current flowing through the wire? What is resistance? I would appreciate it very much if you could answer these questions,



Electrical resistance is the opposition offered by a conductor to the passage of an electric current through it. Resistance to DC or low frequency AC currents in a given material at a given temperature is proportional to the length of the conductor and inversely proportional to its cross-sectional area. In most materials an increase in temperature causes an increase in resistance so as you are passing a current to measure the resistance you are changing the resistance you are trying to measure. You can come close to measuring resistance by measuring the current for a given voltage as long as you keep the current low so as to minimize heating. For more precise measurements you need to arrange an apparatus so there is no current through the measured element as in a bridge circuit.