Energy Transfer

Energy - Devices - Lighting.

There are different forms of lighting.
These include a traditional filament lamp called a GLS (general lighting service)
a more modern energy saving bulb called a compact fluorescent lamp (CFL)
or a light emitting diode (LED).

A filament lamp might be supplied with 6000J in a minute
and produce 1200J of light.
The efficiency is (1200 ÷ 6000) x 100
= 20 %.

An energy saving bulb is a small fluorescent lighting tube
which may have a spiral or be folded four times
and sometimes has a round glass bulb around it.
An energy saving bulb might be supplied with 1500J in a minute
and produce 1200J of light.
The efficiency is (1200 ÷ 1500) x 100
= 80 %.
The wasted energy for both bulbs is heat.

The energy saving bulb (CFL) is more expensive to buy
than the GLS filament lamp but cheaper to use
(see cost-effectiveness).

An alternative light source is the LED (light emitting diode).
These are being used more as time goes by.
LED lights are more expensive to buy but use less current
and last much longer, 10 to 20 years is not uncommon.
See the circuit symbol for a LED.

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