A centrifuge is a piece of equipment, generally driven by an electric motor (but some older models are still spun with hand), that puts an object in rotation around a fixed axis, applying a force perpendicular to the axis. The centrifuge works using the sedimentation principle, where the centripetal acceleration causes heavier particles to move out along the radial direction (the bottom of the tube). By the same token, lighter objects will tend to move to the top (of the tube; in the rotating picture, move to the center).
In the picture shown, the floor model unit, called the rotor, has fixed holes drilled at an angle (to the vertical). Test tubes are placed in these slots and the rotor is spun. As the centrifugal force is in the horizontal plane and the tubes are fixed at an angle, the particles have to travel only a little distance before they hit the wall and drop down to the bottom. These angle rotors are very popular in the lab for routine use.
Second Source Parts
Second Source Service