## Voltage, Current and Resistance

The relationship between Voltage, Current and Resistance forms the basis of Ohm’s law which in a linear circuit states that if we increase the voltage, the current goes up and if we increase the resistance, the current goes down. Then we can see that current flow around a circuit is directly proportional ( ∝ ) to voltage, ( V↑ causes I↑ ) but inversely proportional ( 1/∝ ) to resistance as, ( R↑ causes I↓ ).

- Voltage or potential difference is the measure of potential energy between two points in a circuit and is commonly referred to as its “
**volt drop**”. - When a voltage source is connected to a closed loop circuit the voltage will produce a current flowing around the circuit.
- In DC voltage sources the symbols +ve (positive) and -ve (negative) are used to denote the polarity of the voltage supply.
- Voltage is measured in “
**Volts**” and has the symbol “ V ” for voltage or “ E ” for energy. - Current flow is a combination of electron flow and hole flow through a circuit.
- Current is the continuous and uniform flow of charge around the circuit and is measured in “
**Amperes**” or “**Amps**” and has the symbol “ I ”. - Resistance is the opposition to current flowing around a circuit.
- Low values of resistance implies a conductor and high values of resistance implies an insulator.
- Resistance is measured in “
**Ohms**” and has the Greek symbol “ Ω ” or the letter “ R ”.