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The ratio of the mean spherical candle power to the mean horizontal candle power is called ________.
reduction factor
utilization factor
beam factor
lamp efficiency
reduction factor
The reduction factor is defined as the ratio of the Mean Spherical Candle Power (MSCP) to the Mean Horizontal Candle Power (MHCP) of a light source. It serves as a measure of the distribution of light intensity from a lamp in all directions compared to its intensity in the horizontal plane.
IS 1885 (Part 16/Sec 1): 1974 (Electrotechnical Vocabulary: Lighting)
The reduction factor is defined as the ratio of the Mean Spherical Candle Power (MSCP) to the Mean Horizontal Candle Power (MHCP) of a light source. It serves as a measure of the distribution of light intensity from a lamp in all directions compared to its intensity in the horizontal plane.
Reduction┬аFactor=MHCPMSCPтАЛ
MSCP=4╧АTotal┬аFlux┬аin┬аLumensтАЛ
In practical incandescent lamps, the filament shape and construction cause light to be emitted non-uniformly. The MHCP represents the average intensity in the horizontal plane, while the MSCP represents the total luminous flux divided by 4╧А. The ratio helps in quantifying how effectively the source distributes light in three-dimensional space compared to the equatorial plane.
For an ideal point source radiating uniformly in all directions, the reduction factor is equal to 1.
For practical vacuum lamps, the reduction factor typically ranges between 0.75 and 0.80.
For gas-filled lamps, the reduction factor is usually lower because of the obstruction caused by the lamp mounting and filament geometry.
Provides a simple coefficient to characterize the polar distribution of a lamp.
Useful for calculating the total light output of a source from horizontal intensity measurements.
It is a static value and does not account for the luminaire or reflectors used in actual installations.
Limited utility for complex LED or modern directional light sources.
Determining total lumen output from measured candle power.
Comparison of light distribution characteristics of different incandescent lamp types.
Utilization factor is defined as the ratio of lumens reaching the working plane to the total lumens emitted by the lamp.
Beam factor is used for projectors or floodlights, defined as the ratio of lumens in the beam to the lumens from the source.
Lamp efficiency is the ratio of the total luminous flux emitted by the lamp to the power consumed by the lamp (measured in lumens per watt).
A is correct тАФ The reduction factor is specifically the ratio of the mean spherical candle power (MSCP) to the mean horizontal candle power (MHCP).
Remember that MSCP relates to total flux (4╧А steradians), whereas MHCP relates only to the horizontal circle (2╧А radians).
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