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Answer.

Resistance of conductor is the opposition flow to an electric current. As current flows through the circuit it encounters some opposing force. This force determines the amount of current flowing in an electric device.

The property of conductors that oppose the flow of electric charges depends on the relationship between current and voltage across their ends as discovered by George Ohm. The resistance of a conductor is affected by the following factors:

1. Length of the conductor; The longer the wire, the higher the resistance, short lengths of wire produce resistors of low resistance while long lengths of the same wire are good for high – value resistance.

2. Temperature; An increase in temperature of a conductor means an increase in its resistance and vice versa. This is important in resistance thermometers. The resistance of metal conductor increases with increase in temperature.

3. Types of material; The conducting ability of the material has to be considered. A chrome wire has more resistance than a copper wire of the same dimension. That is why copper is mostly used for connecting wire.

4. Cross – sectional area; A thin wire has more resistance than a thick conductor. The filament of a bulb is made of very thin tang stem wire. It therefore has a high melting point. With all other factors being equal, a long wire has more resistance than a short wire and thin wire has more resistance than a thick one. Therefore resistance of a conductor varies depending on the current flow.

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