Define 1 Ampere.

Define 1 J.

Define 1 dioptre of power of a lens

Define 1 Henry.

Define 1 Newton.

Two long straight thin conductors carrying currents I_1 and I_2 respectively along the same direction are placed parallel to each other in air. Derive an expression for the force per unit length acting on any one of the conductors and hence define one ampere current.

Define an image.

Define species.