Continuous and rapid variations in the load current magnitude which causes voltage variations is known as

• A. Harmonics
• B. Voltage sag
• C. Voltage distortion
• D. Flicker

Answer: (D)

When voltage changes occur in rapid succession, with magnitudes large enough to cause lighting level variations.
The human eye-brain response is most sensitive to periodic r.m.s. voltage changes that occur at around 8 - 10 cycles per second.