What instrument is used to measure rotor speed during centrifuge calibration?

• A. Tachometer
• B. Thermometer
• C. Barometer
• D. Hygrometer

Answer: (A)

To verify centrifuge rotor speed during calibration, you need an instrument that directly reports how fast the rotor is turning, typically in revolutions per minute. A tachometer is designed for this purpose, providing an RPM readout by detecting the passage of marked points or using optical/magnetic sensing. This direct speed measurement is essential to ensure the centrifuge’s indicated speed matches the actual rotor speed, which is crucial for accurate performance and proper separation. The other devices measure temperature, pressure, or humidity—quantities unrelated to rotational speed—so they don’t serve the calibration need. Therefore, a tachometer is the appropriate instrument.