Fields & Static (AQA GCSE Physics)

Fields & Static

• Objects with static charge create an electric field in the space around them

  • If other charges enter the field then they will experience an electric force, attracting or repelling them from the object

• Therefore, an electric field can be defined as:

  A region in which a charged object will experience an electric force

• Electric fields are represented by electric field lines that are always in the direction of positive to negative

• The electric field lines for a charged, isolated sphere, such as a spherical conductor:

  • Point away from the centre of a positive sphere

  • Point towards the centre of a negative sphere

• A uniform electric field, such as that between two parallel plates, are straight parallel lines from positive to negative:

Electric field lines between two parallel plates

• The electric field pattern between two oppositely charged spheres (or point charges) is slightly different and looks like:

Electric field pattern for two opposite charges

• The electric field helps to explain the non-contact force between charged objects since the electric field cannot be seen, but can be detected by another charged object that moves within that field due to the electric force

  • This is a non-contact force because the charged objects do not touch for the force to be exerted

• If an electric field becomes strong enough, the charges are forced through insulators such as air, creating a spark

  • This is what happens for example, when a charged person touches a conductor

• The charged particles will travel towards areas with the opposite charge

Positive and negative charges will travel towards the opposite charge, creating a spark