Ohm's Law

Ohm's Law is the basic law of electrical engineering which was discovered by the German Scientist George Simon Ohm and it was named as Ohm's Law after its discoverer.

Ohm's Law states that :

The current flowing through a conductor is directly proportional to the voltage provided the resistance of the conductor remains constant. This means that the current flowing through a conductor increases when the voltage applied across the conductor increases and vice versa provided the resistance of the conductor remains constant which is mathematically expressed as I ∝ V.

Ohm's Law also states that :

The current flowing through a conductor is inversely proportional to the resistance provided the voltage applied across the conductor remains constant. This means that the current flowing through a conductor decreases when the resistance of the conductor increases and vice versa provided the voltage applied across the conductor remains constant which is mathematically expressed as I ∝ 1 / R.

Therefore, according to the Ohm's Law, current is directly proportional to voltage and it is inversely proportional to resistance which is mathematically expressed as I = V / R.

Where

I = Current In Ampere.

V= Voltage In Volt.

R = Resistance In Ohm.

When any two of the three electrical quantities viz. current, voltage and resistance are available, then the third electrical quantity can be found out by slight mathematical manipulation as shown in the following figure.

When the value of voltage is in volt and the value of resistance is in ohm then the value of current will be ampere.

When the value of voltage is in volt and the value of resistance is in kilo ohm then the value of current will be in milli ampere.

When the value of voltage is in volt and the value of resistance is in mega ohm then the value of current will be in micro ampere.

Current, Voltage, Resistance and Power are four electrical quantities. When any two of the four electrical quantities are available then the third and the fourth required electrical quantity can be easily found by the following Ohm's Law Formula Wheel. According to the four electrical quantities viz. Current (I), Voltage (V), Resistance (R) and Power (P), this formula wheel is divided into four sections and each section has three formulas.

Adopt the following steps to find out the required electrical quantity by using the above Ohm's Law Formula Wheel when any two of the four electrical quantities are available.

1) Decide which electrical quantity do you want to find out.

2) Select the required section of the formula wheel for the calculation of the required electrical quantity.

3) Find out which two electrical quantities are available with you.

4) Select the required formula according to the available electrical quantities.

5) Calculate the required electrical quantity according to the selected formula.

Mock Test On Ohm's Law