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Energy Transfer

Energy - Devices - Light Bulb.

A light bulb may be a traditional filament lamp
called a GLS (general lighting service)
or a more modern energy saving bulb
called a compact fluorescent lamp (CFL).

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 is more expensive to buy but cheaper to use
(see cost-effectiveness).

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