Fluorescence

Question 1

What are the advantages and disadvantages of using a fluorescent bulb? (2 of each)

Answer 1

Advantages:

• Uses less energy than a filament bulb for the same light intensity
• Longer lasting compared to filament bulbs

Disadvantages:

• Mercury in the fluorescent lamp is toxic.
• More expensive than filament bulbs

Question 2

How does electrical current get converted into visible light in a fluorescent lamp? (4 stages)

Answer 2

• Electrons collide with mercury atoms which are ionised
• The positive mercury atoms collect electrons and return to the ground state, emitting a UV photon.
• The UV photon interacts with the fluorescent material around the tube.
• The electrons in the fluorescent coating of the tube becomes excited and then return to the ground state, emitting photons of visible light