Distance of closest approach - the smallest distance between an incoming particle and the target in a scattering experiment

Doppler effect - the change in measured frequency when there is relative motion between source and observer down a flavour of quark with electric charge

Drag force - a force of resistance to motion

Dynamic or kinetic friction - a force opposing motion when a body moves

Eddy currents - small induced currents in a conductor where the flux is changing that dissipate energy

Efficiency - the ratio of useful work or power to input work or power

Elastic potential energy - the energy stored in a spring when it is compressed or stretched

Electric charge - a conserved property ot matter

Electric field - the field produced by electric charges

Electric field strength - the electric force per unit charge experienced by a small point positive charge