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Electrical Applications 2 by David W. Tyler

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112 Illumination
Lamp/cd
^d metres
Light rays
very nearly
parallel
Figure 7.6
7=2000 cd
10m
20 m
Figure 7.7
Example 3. Calculate
the
level
of
illumination (illuminance)
on
a
horizontal surface due to
a
single lamp with uniform light
radiating capability of
2000
cd mounted 10 m above the surface
at points:
(a) Immediately below the lamp.
(b)
10 m
from this point on the horizontal surface.
(c)
20 m
from the original point on the horizontal surface.
(a) Since the lamp has uniform light radiating capability,
the
value 2000 cd may be used throughout.
Immediately