Question

Light energy is obtained in fluorescent lamps and in CFL as result of electron emission. Yet, the process of electron emission is different in both cases. What is the difference?

Answer 1

Hint: Construction and working of fluorescent lamp and compact fluorescent lamp should be known. Also, in that which material is used nowadays due to which electron emission takes place and light energy is obtained.

Complete step-by-step answer:
First, we should know the working of fluorescent lamps and CFL. So, first explain the working and construction of fluorescent lamps.
Fluorescent Lamp: It generates light from collisions in a hot gar of free accelerated electrons with atoms. Specially in mercury, in which electrons are bumped up to higher energy levels and then fall back while emitting at two UV emissions lines of wavelength 254nm and 185 nm. This created UV radiation is then converted into visible light by excitation of fluorescent coating on the glass envelope of the lamp. This coating is the reason for light emission in desired range. In this case, the spectral emission depends on the phosphor coating. This lamp can be enriched for blue light having wavelengths in the range of 400 nm to 500 nm.
Compact Fluorescent Lamp (CFL)- In this case, an electric current is driven through a tube wire filament and heats the filament until it starts to glow. An electric current is driven through a tube containing Argon and a small amount of mercury vapor. This generates invisible Ultraviolet light that excites phosphor coating on the inside tube which emits light energy.
So, in both the cases electron emission is the same but inside the process is totally different.

Additional information:
This entire process of CFL takes 30 seconds to 3 minutes to complete, which is why it takes longer than other lights to become fully lit. Most CFLs today use electronic ballasts, which do not make sounds like buzz or hum.

Note: CFLs with decorative covers like globe or reflector shapes have unique design challenges that result in the trade-off of slower warm up time. This is the reason CFLs take longer than bare spirals to reach full brightness.