luminous object: something that produces its own light

The Moon is bright only because it reflects the Sun’s light. Therefore, theMoon is NOT luminous.

1. Incandescence: light that is emitted from a very hot object

sodium vapour lamps

a) electric discharge

neon lights

2. Luminescence: light that is generated without heating the object

- types:

Bohr Model of the Hydrogen Atom

LEDs(light-emitting diodes)

b) chemiluminescence: light that is produced by a chemical reaction without a rise in temperature

c) bioluminescence: light that is produced by a biochemical reaction in a living organism

and mercury

d) fluorescence: light that is emitted during exposure of the source to ultraviolet (UV) light

compact fluorescent light (CFL) bulbtubular fluorescent light bulb

Efficiency of Fluorescent Vs. Incandescent Bulbs

Even though fluorescent bulbs are 4X as efficient as incandescentbulbs (20% vs. 5%) , some people don’t like them because:

they find the light from fluorescent bulbs to be harsh.

these lamps contain small amounts of mercury vapour, a toxic metal.

Because they contain mercury, used fluorescent lamps CANNOT be thrownin the garbage.

In Oakville, Rona & The Home Depotwill take back your used fluorescent bulbs.

Uses of Fluorescence

forensic science

black light theatre

fluorescent fish

money

e) phosphorescence: light that is emitted due to exposure of the source to UV light, and that continues to be emitted for some time in the absence of the UV light