Electric Fields Electric Fields What is a field

Electric Fields

Electric Fields What is a field? • A field is a physical quantity that has a value for each point in space and time. • For example, temperature at the surface of the Earth is a scalar field, it has a single value at every point on the Earth. Wind measurements give a vector field, each point has both a magnitude (wind speed) and direction.

Electric Fields What is a field? • We represent vector fields using field lines. • The lines themselves tell us about the direction of the field. • The spacing of the lines tell us the strength of the field; the closer together the lines are, the stronger the field is at that point.

Radial Electric Fields • The field around a point charge is radial, so the force the charge would experience depends on the distance from the centre. . q

Radial Electric Fields • If two charges are present, their fields will interact in a similar way to magnetic fields.

Uniform Electric Fields • A uniform field can be produced between two metal plates by connecting them to a cell. 300 V 0 V

Charges in Electric Fields • Charged particles move through electric fields like projectiles. The particle will experience a force parallel to the field lines and accelerate in this direction at a constant rate. The path is a parabola.

Charges in Electric Fields • Charged particles move through electric fields like projectiles. The particle will experience a force parallel to the field lines and accelerate in this direction at a constant rate. The path is a parabola.

Charges in magnetic fields • Forces act on charged particles in a magnetic field. • According to Fleming’s left hand rule, the force is always perpendicular to the direction of travel – this results in circular motion. p × × ×