A microcentrifuge, used with small samples (1-2 mL)
A bench centrifuge, to separate larger samples (15 mL or so)
The word centrifuge comes form the Latin centri- (center) + fugere (to flee). A centrifuge works by angling the tips of the tubes outward and spinning them. Centrifugal force causes the heavier particles to sink to the bottom of the tube, forming a pellet. The lighter particles float on top. If the top layer is a liquid, it is called a supernatant and can be removed by pipetting.