Revision Notes for Electricity

Components of an Electricical System

1. Bulb

- parts of bulb :
i) glass casing (transparent- to allow light to pass through)
ii) metal casing (to allow electricity to pass through)
iii) Metal tip (allow electricity to pass through)
iv) Tungsten ( Poor conductor of electricity but is able to withstand high temperature so that the wire will not melt and electricity still can pass through)

- know how the wires are connected inside the metal casing. (that is, one end of the tungsten is connected to the metal casing and the other end to the metal tip)


2. Wires
- usually consist of wire (usually copper - good conductor of electricity) and outer covering (usually rubber - flexible for bending)


3. Cells/ Batteries
- to supply electricity for the system
- Arrangement of Batteries can affect the brightness of the bulb
i) Series arrangement
* bulb is brighter
* if one battery is removed, the bulb will not light up

ii) Parallel arrangement
* bulb has the same brightness
* If one battery is removed, the bulb will still light up.

4. Switches
- function/use : to control the flow of electricity in a circuit. (to open or close a circuit)

- Arrangement of switches
i) in series - the switch will control the main flow of electricity in the circuit
ii) in parallel - the switch will control the flow of electricity in that particular smaller loop.


Conductors of Electricity

Materials can be classified in the following way:

1. Insulators of electricity
- does not allow electricity to pass through at all
- Eg usually the non-metals such as wood, plastic, glass

2. Good conductors of electricity
- allows electricity to pass through easily
- Eg usually the metals such as copper, silver, aluminium

3. Poor conductor of electricity
- allows electricity to pass through but not so easily.
- Eg tungsten, nichrome