Suppose the photodetector of an optical tachometer detects a time interval of 0.05 seconds between the leading edges of the pulses created by the reflective stripe during shaft rotation. What is the rpm of the shaft?

Correct Answer: Option C — 1200 rpm

Frequency is the reciprocal of the time interval (1 / 0.05 seconds = 20 Hz). To convert frequency in Hertz to revolutions per minute, multiply by 60 seconds. 20 Hz multiplied by 60 equals 1200 rpm, representing the rotational speed of the shaft detected by the optical sensor.