Although speed and velocity are often words used interchangeably, in physics, they are distinct concepts. Velocity (v) is a vector quantity that measures displacement (or change in position, Δs) over the change in time (Δt), represented by the equation v = Δs/Δt.
A circuit which has a battery in it will not allow electricity to flow through it. A device called a switch can be used to complete a circuit so that other devices can be switched on or off.
