An electric field is a region around a charged object where another charged object feels a force. This explains how charged objects can attract or repel without touching: the force is exerted through the electric field.
Field lines show the direction of the force on a positive charge. They point away from a positive charge and towards a negative charge. So a positive charge is repelled by another positive charge and attracted by a negative charge. The field is stronger closer to the charge, where the lines are closer together, and the force on another charge is larger there.
You can see a field pattern by sprinkling semolina on castor oil between two charged electrodes. The grains line up along the field lines. A very strong field can pull electrons from air molecules, so the air conducts and a spark jumps.
