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17 Cards in this Set
- Front
- Back
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State the equation for luminaire efficiency . |
Luminaire efficiency = luminous flux (lm) / power input (w) |
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State 3 ways to limit stroboscopic effect in fluorescent light fittings |
Operating pairs of tubes from special twin ballasts. Connecting adjacent single tube fittings on different phases Using a mixture of incandescent and fluorescent lamps Capacitor in series offsets the twin tube light fitting |
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Two components of a glow starter |
Bi-metal strip / contacts Radio interference capacitor |
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List the two gases found in a glow starter |
Helium and hydrogen |
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Two functions of a ballast in a fluorescent light fitting |
Limits the amount of current flowing through the electrodes Provides a voltage surge of high enough potential to initiate a discharge |
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State the two capacitors found in the fluorescent light fitting |
Power factor correction Radio interference (starter) Stroboscopic |
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Why does a fluorescent fitting have a low p.f |
Ballast , highly inductive choke |
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List the two gases found in a fluorescent tube |
Mercury and argon |
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Define luminous intensity |
Luminous intensity means the luminous flux per unit solid angle in a specified direction |
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Define luminous flux |
The rate at which light energy is being enjoyed by a light source , measured in lumens (lm) |
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Define illumination |
Is the lighting of an object or surface |
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Define Luminous efficiency |
The ratio of lumens of light produced to power input in watts |
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Define the term glare |
Is the excessive contrast of brightness or colour |
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List four requirements for good illumination |
Light level is adequate Colour Brightness Light should be as even as possible |
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State two basic methods of producing light |
Passing a current through a tungsten wire filament Passing a current through a gas |
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Average life of incandescent light |
1000 hrs |
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Four factors that determine incandescents life span |
Mounting position Vibration Ventilation Variation of supply voltage |
