Electric Field Patterns
Physics: Cambridge International GCSE Supplement, topic 4.2.6
Electric Field Patterns
An electric field is the region around a charged object where other charges experience a force.
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Patterns
- The direction of the field lines shows the direction of the force on a positive test charge.
- Field lines always go from positive to negative.
- The density of field lines represents the strength of the field (closer lines = stronger field).
Around a point charge
- A positive point charge produces field lines that radiate outwards equally in all directions.
- A negative point charge produces field lines that point inwards towards the charge.
- The pattern is symmetrical (like the spokes of a wheel).
Around a charged conducting sphere
- Outside the sphere, the field looks exactly the same as for a point charge (outward for positive, inward for negative).
- This happens because the sphere’s charge is distributed uniformly on the surface.
Between two oppositely charged parallel conducting plates
- Field lines run straight, parallel, and evenly spaced from the positive plate to the negative plate.
- This shows the field is uniform: the strength is the same everywhere between the plates.
- This uniform field is important in devices like particle accelerators and cathode ray tubes.
Test yourself on Electric Field Patterns
Which way do electric field lines point?
If a positive point charge exerts an electric field, which direction will the arrows point?