The Ohms Law

 

What is Ohm’s Law?

 

Ohm’s Law states that the electrical current flowing through any conductor is directly proportional to the potential difference (voltage) between its ends, assuming the physical conditions of the conductor do not change (for example, temperature). The relationship between voltage (V) and current (I) and the resistance (R) in an electrical circuit was first discovered by the German physicist George Simon Ohm.

Mathematically, Ohm’s Law can be expressed as I ∝ V

Introducing the constant of proportionality, the resistance R in the above equation, we get

I = V/R or V = I * R

Where R is the resistance of the conductor in Ohm (Ω)

              I is the current through the conductor in Amperes (A)

              V is the voltage or potential difference measured across the conductor in Volts (V)

Ohm’s Law is applicable to both DC and AC

Let us have better understanding of Ohm’s Law by using some analogies.

Consider a water tank placed at a certain height above the ground. There is a hose at the bottom of the water tank as shown in the image below.

 

Source: Internet

Let’s assume Water Pressure = Voltage; Water Flow = Current; and Restrictors = Resistance. Thus, the water flow (current) through the aperture/hose is proportional to the difference in water pressure (voltage) across the restrictor (resistance).

Similarly, in an electric circuit, the current flowing through a conductor or resistor between two points is directly proportional to the difference in voltage or potential difference across the conductor or resistor.

Ohm’s Law formula for Power

The power transferred is the product of supply voltage and the electric current i.e., P = V * I.

                        Now putting V = I * R, we can say P = I * R * I 

                                                                i.e, P = I(square) * R.

This formula is known as the ohmic loss formula or resistive heating formula.