• Ohm's law states that, "The potential difference V across the ends of a given metallic wire in an electric circuit is directly proportional to the current flowing through it, provided its temperature remains the same".
i.e V= I.R
• R is constant for a given metallic wire at a given temperature, and this constant is named resistance. It is the property of a conductor to resist the flow of charges through it.
• Its SI unit is ohm which is denoted as ?.
• If we plot the V-I graph for a conductor, then it shows a linear nature.
• The slope of the graph gives the resistance of the conductor.
• If the potential difference across two ends of conductor is 1 V and the current through it is 1 A, then the resistance of the conductor is 1 ?.
• In practice, the current needs to be increased or decreased. This is achieved by a variable resistor
called a rheostat.
• The motion of electrons/charges in a conductor is retarded by its resistance.
• A conductor offering less resistance is called a good conductor, and a conductor offering high resistance is called a poor conductor. An insulator offers a very high resistance.
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