Voltage, Current, Resistance, Power, and Energy are the basic electrical properties. In this post you’ll learn fundamentals of these properties and their units.
Let’s consider a basic electric circuit that comprises an energy source, a switch, a lamp, and wires used to connect circuit elements.
At the instant when the switch is closed, charges begin to flow in the circuit and switch on the lamp. The flow of charges is technically termed as current.
But what causes this flow of charges? The answer is volts
The motion of the current is actually caused by the voltage source (which is battery) in our case
Besides voltage and current there is another property, namely the resistance. Resistance is the property of material which governs flow of current. Resistance is inversely related to the current. i.e the higher the resistance, the lower will be the current flow, and vice versa.
Aside from voltage, current, and resistance, the fourth property of Electric power which is defined as the produce of voltage times current. Mathematically, P = VI
Energy is defined as product of power and time. Mathematically W = P * t
The table below lists all these basic properties alongside their SI units:
| Quantity | Symbol | Unit | Abbreviation |
|---|---|---|---|
| Current | I | ampere | A |
| Voltage | V | volts | V |
| Resistance | R | ohms | Ω |
| Power | P | watt | W |
| Energy | W | joule | J |