Electricity - 2.5.2 Electric Fields (GCSE Physics AQA)

Electric Fields

Electric Fields

• Charged objects create electric fields. If an object is electrically charged, it will create an electric field around itself. An electric field is very similar to a magnetic field, but instead of a magnet at the centre of the field, we have a charged particle.
• The strength of the electric field varies. The electric field strength will vary depending on the distance from the object. As you get further away from the object, the field strength gets weaker. Similarly, the closer you get to the object, the stronger the field strength.

• Charged objects experience a force in an electric field. If we place one object into another object’s electric field, then it will experience a force. The force could be an attractive or repulsive as discussed in the previous section.

• Force strength varies with distance of objects in an electric field. As the two objects get closer together in an electric field, the force between them will get stronger. Similarly, as two objects get further away from each other, the force between them will get weaker.
• Electric fields can cause sparking. Similar to charge difference, electric fields can cause sparking. The larger the charge difference, the stronger the electric field. The stronger electric field means that electrons from air particles are removed. By removing the electrons, the air becomes much more conductive, allowing a current to flow through it easily. This leads to the production of a spark.

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Drawing Electric Field Patterns

For AQA exams, we need to be able to draw the electric field pattern for an isolated charged sphere. There are a few important rules to remember:

1. Field lines are drawn as straight lines from a charged particle (like the spokes of a wheel).
2. Field lines always point from positive to negative.
3. The sphere itself can either has a positive or negative charge.

A positively charged sphere will have the field lines pointing away from it.

A negatively charged sphere will have the field lines pointing towards it.