Van de Graaff generator – an electrostatic generator which separates charges to produce a large potential difference(see figure 17.6)

Varifocal lens– a lens which must be refocused whenever you change its focal length

Vector - a quantity that is specified by both a magnitude and a direction

Vector sum – the resultant vector when two or more vectors are added

Velocity– a quantity that describes both the direction and speed of motion

Virtual image – an image formed at a point where the light appears to have come from

Viscosity – that property of a fluid that indicates its internal friction

Volt– the unit of electric potential; a joule per coulomb

Voltmeter – an instrument for measuring potential difference or voltage