State the Ohm.s law. Explain how it is used to define the SI unit of r

1.	State the Ohm.s law. Explain how it is used to define the SI unit of resistance.
Answer» Solution :If I is the current flowing through a conductor and V is the potential difference (or voltage) across its ENDS, then according to Ohm.s law, I `prop` V (at constant temperature). This can also be written as, `V prop I` `:.` V = (constant) I `{:( :. V/I = "constant"),( ""= R),( :. V = IR):}}`... ...(12.4) In equation (12.4), R is constant for the given metallic wire at a given temperature and is called its resistance. Resistance is the property of a conductor to oppose the flow of CHARGES through it. The SI unit of resistance is ohm. It is represented by the GREEK letter `Omega` (Omega). According to Ohm.s law, `R = V/t`...... (12.5) Definition of the SI unit of resistance : If the potential difference across the two ends of a conductor is IV and the current through it is 1 A, then the resistance R of the conductor is `1 Omega`. `i.e., 1" ohm" = (1 "volt")/(1 " AMPERE") (1 Omega = 1V//1A)`

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