# Electric fields 22.1

?
• Electric Fields 22.1
• Electric field strength
• The force experienced per unit positive charge at that point
• E=F/Q, where F is the force experienced by the positive charge Q. The SI unit is N/C and electric field strength is a vector quantity
• Field patterns
• Mapped using lines of force
• The direction of a field at a point shows the direction of the force experienced by a small positive charge at that point
• The field strength is indicated by the separation between the field lines
• Key points
• A uniform electric field has equally spaced field lines. the electric field between 2 oppositely charged parallel plates is uniform
• Electric field lines are always perpendicular to the surface of a conductor
• A radial field has straight field lines that converge to a point at the centre of the charged object. The filed strength decreases with an increase in distance from the object
• A uniformly charged sphere can be modelled as a point charge at its centre