The effects of ac current is related to amount of frequency strongly. If this amount be very low, the flicker of lamp illumination will be observable. The typical frequency range of observable flicker is from 0.5 to 30.0 Hz, with observable magnitudes starting at less than 1.0 percent. The human eye is more sensitive to luminance fluctuations in the 5- to 10-Hz range. As the frequency of flicker increases or decreases away from this range, the human eye generally becomes more tolerable of fluctuations. In discharge type lamp the traditional ballasts produce 100 pulses ( in 50 HZ) of current every second, and the phosphor