A fluorescent light bulb has a glass tube, a low-pressure gas, and some electrodes. When a free charge is injected through high temperature or high voltage the lighting process begins. The high violated applied to the electrodes created an electric field which enables current to flow via the plasma. The current excites gas atoms which collide with electrons from the cathodes to emit light through fluorescence. In a nutshell, an atom has electrons which orbit the nucleus. Each orbital has at most two electrons and has both potential and kinetic energy.
In normal cases, the electrons are found in the lower energy orbital known as the ground state. However, when electrons are excited, they move to a higher energy level state known as the excited state. The electrons emit lights in the form of photons when changing the orbital. The light produced in the form of photons has a short wavelength thus it is not visible in the eyes of human beings. In a collision process, electrons lose some energy and excite atoms; such energy is lost through radiation transmission. After losing some energy, electrons move back to their orbitals and releases photon when reverting to their normal state. In this process, the absorbed radiations are found in the ultraviolet region of the spectrum which is invisible to people. When the voltage is applied to the fluorescent lamps. the starter (timed switched) allow current to flow through the filament at the end of the tube, the current causes the starter contact to heat up and opens, thus interrupting the flow of current. The tube lights since the lighted fluorescent tubes have a low resistance. The starter, therefore, helps the lamp to light and choke serve as a current limiter without the choke, the arc is a short circuit between the filament and this short circuit contain a lot of currents. the current either vaporizes the filament or causes the bulb to explodes.
An LED source is often proprietary to the fixture manufacturer. That means purchasing a source from a company that is not used to supplying items in small quantities. They will need to know the model number of the fixture, and possibly when it was ordered, and also by whom. So good luck obtaining that information. Then they will provide a price after a week or so, which will be between $25 – 180 per chip. Then you will pick yourself up off the floor and order one. Then when it arrives you find that you need to unscrew the original chip off the board, without damaging the ceiling, all through a 3″ aperture. Then, after you have damaged the ceiling and have threaded the screw, wasting an hour, you say the hell with it and hire an electrician at $200 to swap the chip. Finally, the light turns on, but wait, that chip is noticeably brighter and different hue than all the other lights? Well, since LED chips have a light loss factor, and have been running for some time, the fresh chip is brighter. And because that fresh chip came from a different binning cycle than the original set, it is a different color.