Electricity is a very interesting segment of physics an in this segment Ohm’s Law is very Important and fundamental law. This was discovered by a Germen Physicist Mr. Gorge Simon Ohm. That’s you know as Ohm’s Law.
As per definition Ohms Law is “The current through a conductor between two points is directly proportional to the voltage across the two points.”
Current α Voltage
And after some research and observation it is concluded that “The current through a conductor between two points is equal to the voltage across the two points divided by resistance.”
Current = Voltage / Resistance
So for any DC Circuit you can use above formula for finding any missing value.
For remembering Ohms Law you should understand resistance, Current and Voltage.
In a very simple notation, Resistance is electron’s problem in traveling; Voltage is power or force which is continuously pushes electron and Current is flow of electrons.
So as per Ohm’s Law
If resistance is high more power is required for current flow or in other case suppose there is very low power or force (voltage), resistance is fix so flow (current) will be low.
But you know that all devices don’t follow Ohm’s Law. These devices are called Non-Ohmic devices such as transistors or diodes.
In our home we are paying a lot of money on electricity bill so do you ever think that for what we are paying? Actually this is due to our electric appliances. These electric appliances consume some electric power and for that we are paying.
Now come second point, how to calculate consumed power by any appliances?
Here you have to understand concept of Electric Power. Here I will discuss only DC power consumption, for AC I will share in other article.
Electric Power (Symbol P) in any circuit is the rate at which electric energy consumed or absorbed. It is multiplication of Current and Voltage and it is measured in unit “Watt (Symbol W)”.
Its mathematical formula is
Power (P) = Voltage (V) X Current (I)
So hope that now Ohm’s Law will be clear to you. you can also visit wikipedia for more clarification