2.3 Energy Charge

REVISION NOTES

IGCSE Edexcel Physics

2.3.1P Identify common materials that are electrical conductors or insulators, including metals and plastics

Conductors:

Insulators:

2.3.2P Practical: investigate how insulating materials can be charged by friction

Apparatus needed:

Independent variable: Material of rod

Dependent variable: Charge of rod

Method:

Attach the polythene rod to a wooden stand and let it hang from the string and cradle
Attach another rod to another wooden stand and let it hang from the string and cradle
Rub both ends of the polythene rod with a cloth
Rub both ends of other rod with same cloth
If the rods move towards each other they are oppositely charged
If the rods rotate away from each other they have the same charge

Controlled variables:

2.3.3P explain how positive and negative electrostatic charges are produced on
materials by the loss and gain of electrons

Controlled variables:

2.2.4 Describe the qualitative effect of changing resistance on the current in a circuit

When an object loses electrons, it becomes positively charged

Due to the object originally having a neutral charge
Electrons have a negative charge
Thus taking away negative charge from a neutrally charged object will make it positively charged
0 – (-1) = +1

When an object gains electrons, it will become negatively charged

2.3.5P Know that there are forces of attraction between unlike charges and forces of repulsion between like charges

2.3.6P Explain electrostatic phenomena in terms of the movement of electrons

Opposite charges will attract in order to balance out
Thus protons and electrons will be attracted to each other
Thus objects with more protons than electrons and objects with more electrons than protons will be attracted to each other
This is called an electrostatic force of attraction
Sometimes electrons will travel from one material to another
- Such as from the cloth to the polythene rod

2.3.7P Explain the potential dangers of electrostatic charges, e.g. when fuelling aircraft and tankers

When an aircraft flies through the air friction causes it to become charged with static electricity
When the aircraft lands the electricity wants to ground itself
This can happen as a spark or a flash of electricity
If this happens during refuelling of the aircraft it could cause an explosion
A solution is to earth the aircraft with a good conductor as soon as it lands