Hi guys, today we will be learning about Electricity.
The areas that will be covered include: Current in a circuit, Current and p.d. (potential difference) , Resistance, Ohm's law and mains plug. I hope you find this blog useful.
Current in a circuit
It is only possible for a current to flow through an electrical component when there is potential difference/voltage across the ends of it. Greater the potential difference across a component = greater the current flowing through it.
Current is measured using an ammeter, which is connected with the component in series. The unit that measures current is called Amperes (A).
If the components in a circuit are connected in series, the same current flows through every component.
On the other hand, if components are connected in parallel, then the overall (total) current is the sum of the currents in each loop.
Potential difference and current
Within a series circuit, the amount of current has the same value at any point.
In a parallel circuit, the total current is equal to the sum of the currents in each loop.
Within a series circuit, the total amount of Potential difference isthe sum of the individual potential difference (voltage) over each component.
In a parallel circuit, each loop has the same potential difference (voltage) over it.
Resistance
credit: http://yagitech.blogspot.co.uk
Electrical components resist current that flows through them.
The bigger the resistance on the component, the smaller the current that can be made by a particular potential difference in a circuit.
The Bigger the resistance is, the bigger amount of voltage required to create a certain amount of current.
The total resistance, when the components are set up in series, is the sum of their individual resistances.
Ohm's Law
The current going through a resistor (at a constant temperature) is proportional to the voltage across the resistor.
Unit of current = amperes
unit of resistance = ohms.
Mains plug
Credit: bbc bitesize
U.K. mains supply is around 230 volts and and alternates (changes direction) at 50 Hz (hertz).
Electricity mains could potentially kill you if not used safely.
With a mains cable, there are 2 or 3 inner cores made of copper. This is because copper is a good conductor.
A mains cable has outer layers of plastic. This being because plastic is a good insulator.
Appliances that have a metal case are normally earthed for safety.
If a fault occurred and the live wire was touching the case, a very big current will travel to earth causing the fuse to overload once the switch is turned on.
The cable grip should ensure that the cable is secure in the plug.
An electric 13A plug's case is made of plastic because of it being a good insulator.
As a good conductor, brass is used in the pins of a plug.
Why are the pins of a plug not made from copper?
Brass is less expensive than copper.
Brass does not tarnish easily because it is corrosion resistant.
Brass is rigid. This means that the pins will not bend when the plug is removed from the socket.
Credit to AQA for the information.
Thanks for reading. Hopefully you can take something from this blog and have learnt something interesting today!
