V–I graph for a nichrome wire

Ohm’s Law

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Ohm’s Law

In 1827 a German physicist Georg Simon Ohm found out the relationship between the current and potential difference which is known as Ohm’s Law.

Ohm’s Law

The potential difference (V) across the end of a given metalic wire in an electric circuit is directly porpotional to the current flowing through it provided its temperature remains the same. this is called Ohm’s Law.

potential difference  ∝  electric current                                                                            V  ∝      I

The resistance of a conductor isthe ratio of the flowing current. Its  S.I. unit is Ohm. Represented by the Greek letter  Ω                                               

                                if                             V ∝ I

V–I graph for a nichrome wire.

 Potential difference   = Resistance X Current

Resistance = potential difference / Current

Define 1 Ohm.

If the potential difference across the two ends of a conductor is volt and current through it is 1 A. Then the resistance R , of the conductor is 1 Ohm

1 Ohm = 1 volt / 1 ampere

The current through a resistor is inversely porpotional to its resistance.

What is variable resistance?

A component used to regulate current without changing the voltage source is called variable resistance.

Which device is used to change resistance in the circuit?

A device called rheostat is often used to change the resistance in the circuit.

The electron are not completely free to move within a conductor. They are restrained by the attraction of the atoms among which they move.

Motion of electron through a conductor is resistance is a good conductor.

A componnt of a given size that offer a low resistance is a good conductor.

A conductor having some appereiable resistance is called a resistor.

A component of identical e tat offer a higher resistance is a poor conductor.