Very Short Question and Answers - Ohm’s Law

Ohm’s Law states that the current flowing through a conductor is directly proportional to the potential difference across its ends, provided the temperature and other physical conditions remain constant.

Ohm’s Law is mathematically expressed as V = IR, where V is potential difference, I is current, and R is resistance.

Resistance is the property of a conductor to oppose the flow of electric current. Its SI unit is ohm (Ω).

The temperature (and other physical conditions) must remain constant for Ohm’s Law to hold true.

I = V/R = 20/5 = 4 A.

The V-I graph for an ohmic conductor is a straight line passing through the origin, showing direct proportionality between voltage and current.

The slope of the V-I graph (V divided by I) represents the resistance (R) of the conductor.

Ohmic conductor: metallic wire (like copper wire); Non-ohmic device: incandescent bulb or diode.

Because its temperature increases as more current passes, changing its resistance; hence, Ohm’s law does not apply.

The current is halved because I = V/R.

Voltage is like water pressure, current is like the flow of water, and resistance is like the narrowness of the pipe.

The current also becomes three times as much.

Metallic conductors like copper, iron, etc., usually obey Ohm’s law.

An electric heater works based on Ohm’s law.

Because their resistance changes with applied voltage or current, so the V-I relationship is not linear.

An ‘ohmic’ device obeys Ohm’s Law (has a linear V-I relationship). A ‘non-ohmic’ device does not.

The wire is an ohmic conductor and obeys Ohm’s law.

R = V / I.

The line becomes less steep (slope increases), meaning more voltage is needed for the same current.

R = V/I = 12/2 = 6 Ω.