Swathi asked:

Why do fluorescent lights flicker (tube lights) while Incandescent bulbs don’t , especially when they are switched on..Is it an effect of the pulses as sensed by the retina?

Ans:

If your question is regarding the start up flickering,

the fluorescent lamp requires a very high voltage to start conducting. In a lit up tube light, the conduction is taking place through the gas filled inside the tube. As you know, air is a bad conductor. To make it conducting, it is to be ionized first. This is done by developing a very high potential difference between the two ends of the tube by the combined action of starter and the choke. Starter is a make and break arrangement which makes the supply intermittent. When the supply is disturbed, a huge potential difference is developed and flashes produced inside the tube ionizes the gas inside the tube. After such a few occurrences, the gas will be ionized enough to make the gas conducting. During this process lot of UV radiations are emitted. This strikes the fluorescent coating on the tube which converts UV radiations to visible light. So, the tube light flickers due to the action of starter during the startup time.

But, if your question is with regard to the flickering of a lit up fluorescent lamp, …………. 

I will answer it later