Explain how fluorescent tubes work

Fluorescent tubes are filled with low pressure mercury, when an electric current is passed through, the electrons in mercury are excited and move to a high energy level, this high level state is unstable and so the electron moves back to its original state, but on doing so, it emits an electromagnetic wave with energy equivalent the difference in energy level. This is UV light and the electrons in the phosphor coating inside the fluorescent tube are excited, and releases visible light when the electrons return to its orginal energy state, which provides the glow in fluorescent lights.

Answered by Michael W. Physics tutor

25682 Views

See similar Physics A Level tutors

Related Physics A Level answers

All answers ▸

What is the total capacitance of a circuit containing a 3microfarad capacitor and a 2microfarad capacitor in series.


A wire has length l, cross-sectional area a, resistivity p and resistance R. It is compressed to a third of its original length but its volume and resistivity are constant. Show its new resistance is R/9.


An unknown capacitor is charged to 6v, its maximum value, then discharged through a 1k ohm resistor. If the capacitor voltage is 3v, 0.3 seconds after starting to discharge, what is the capacitance of the unknown capacitor?


Initially, trucks A and B are travelling in opposite directions. A has mass 1000 kg and is travelling at speed 7ms^-1. B has mass 4000kg and is travelling at speed 2ms^-1. What is their speed and direction after collision if they move together?


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo
Cookie Preferences