How does the centrifuge work?

• A. By applying magnetic fields
• B. By gravitational settling
• C. By centrifugal force causing heavier objects to move outward (bottom of the tube)
• D. By manual shaking

Answer: (C)

Centrifugation separates mixtures by density using a strong outward force created when the sample is spun. As the rotor turns, every particle feels a centrifugal push that depends on its mass and density, and how far it sits from the axis. Heavier, denser components experience a greater outward force and push toward the outer edge, collecting at the bottom of the tube, while lighter components stay closer to the center. This is why spinning is so effective at pulling dense materials into a compact pellet or distinct bottom layer, allowing you to separate components like blood cells from plasma or other dense debris.

This mechanism is different from gravitational settling, which relies on gravity alone and is far slower; magnetic separation would require magnetic properties in the particles; and rapid shaking would simply mix components rather than separate them. The key idea is that the centrifugal force generated by rotation, not gravity or manual agitation, drives the density-based separation.