⇒ All an electic CURRENT is is a flow of electrons that move around a circuit

⇒ The VOLTAGE is the driving force that moves the current around i.e. it is, essentally, a kind of electical pressure

⇒ The RESISTANCE is anything that slows down this driving force

• So there is a balance: the voltage tries to push the current around the circuit, whilst the resistance tries to limit the current being pushed around the circuit. Thus the relative size of th evoltage and resistance will determine how big the current is
• Increased voltage = increased current
• Increased resistance = reduced current

⇒ When thinking of current, think of the flow of water within the pipes of your home

⇒ The voltage, when compared to the flow of water, would be like a pump that helps to push the water around

⇒ The resistance would be anything that restricts the flow of the water (i.e. it works against the pump)

⇒ If you were to increase the amount of water being pumped (i.e. the voltage), then more of the water will flow (i.e. the current increases)

⇒ If you were to increase the constrictions within the pipe (i.e. the resistance), then less of the water will flow (i.e. the current reduces)

⇒ Within a conventional current it is said that the current flows from positive to negative

⇒ However, the actual flow of a current is from negative to positive (i.e. it is the opposite of the conventional current)

⇒ Your home will have an alternating current (AC), which means the electricity will keep reversing its direction back and forth

⇒ Using a cathode ray oscilloscope (CRO) it is possible to see electrical current in graphical form

• The CRO would show an AC as a wave with voltage moving from 0 to a maximum positive value, then down to a maximum negative value and back to 0 etc.

⇒ A direct current differs in that it always flows in the same direction

• Using a CRO, the direct current would be displayed as a straight line on a graph because the voltage does not change (and therefore the current stays the same too)
• DC currents are used in batteries, for example

⇒ Also see our notes on:

• Current, Voltage, and Resistance
• The Dynamo Effect
• Power Stations and the National Grid
• Electrical Power
• Waves - The Basics
• Waves
• Refraction
• Dangers of EM Radiation
• Uses of Waves
• Analogue and Digital Signals
• Wind and Solar Energy
• Seismic Waves