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Questions and Answers
What is the unit of illuminance?
What is the unit of illuminance?
- Candela (Cd)
- Lumen per square meter (lm/m²)
- Lumen per steradian (lm/sr)
- Lux (lx) (correct)
A parallel beam of light has an intensity of illumination that varies with distance as:
A parallel beam of light has an intensity of illumination that varies with distance as:
- I ∝ r
- I ∝ 2πr
- I ∝ 1/r (correct)
- I ∝ 1/r²
What is the difference between illuminance and luminance?
What is the difference between illuminance and luminance?
- Illuminance is the luminous flux reflected, while luminance is the luminous flux incident.
- Illuminance is the luminous flux, while luminance is the luminous intensity.
- Illuminance is the luminous flux incident, while luminance is the luminous flux reflected. (correct)
- Illuminance is the luminous intensity, while luminance is the luminous flux.
What is the relation between luminous intensity (L) and illuminance (I) for a unidirectional point source?
What is the relation between luminous intensity (L) and illuminance (I) for a unidirectional point source?
What is Lambert's Cosine Law of Illuminance related to?
What is Lambert's Cosine Law of Illuminance related to?
What is the relationship between illuminance and the angle of incidence of light?
What is the relationship between illuminance and the angle of incidence of light?
What is the principle of photometry?
What is the principle of photometry?
What is the relationship between illuminance and distance from a point source?
What is the relationship between illuminance and distance from a point source?
Why does a 40 watt fluorescent tube give more light than a filament bulb of the same wattage?
Why does a 40 watt fluorescent tube give more light than a filament bulb of the same wattage?
What is the purpose of a photometer?
What is the purpose of a photometer?
What is the ratio of illuminance on the slide to the illuminance on the screen if there is negligible absorption of light by the aperture?
What is the ratio of illuminance on the slide to the illuminance on the screen if there is negligible absorption of light by the aperture?
If the illuminance at a point A on the center of a table is IA, what is the illuminance at a point B on the corner of the table, given that the intensity of illumination follows the inverse square law?
If the illuminance at a point A on the center of a table is IA, what is the illuminance at a point B on the corner of the table, given that the intensity of illumination follows the inverse square law?
What law relates the luminous intensity of a light source to the illuminance at a point on a surface?
What law relates the luminous intensity of a light source to the illuminance at a point on a surface?
If the luminance of a light source is L, what is the illuminance at a point on a surface at a distance r, according to the inverse square law?
If the luminance of a light source is L, what is the illuminance at a point on a surface at a distance r, according to the inverse square law?
What is the ratio of the intensities of illumination at a point on the center of the edge and on the corner of the table, given that the intensity of illumination follows Lambert's Cosine Law?
What is the ratio of the intensities of illumination at a point on the center of the edge and on the corner of the table, given that the intensity of illumination follows Lambert's Cosine Law?
What is the relationship between illuminance and distance for a line source?
What is the relationship between illuminance and distance for a line source?
What is the solid angle subtended by the whole sphere at its centre?
What is the solid angle subtended by the whole sphere at its centre?
A surface is oriented such that the central ray of light makes an angle θ with the normal to the surface. What is the maximum illuminance of the surface?
A surface is oriented such that the central ray of light makes an angle θ with the normal to the surface. What is the maximum illuminance of the surface?
What is the relationship between luminous intensity and illuminance for a unidirectional point source?
What is the relationship between luminous intensity and illuminance for a unidirectional point source?
What is the luminous flux of a source of 1/685 watt emitting monochromatic light of wavelength 5500 Å?
What is the luminous flux of a source of 1/685 watt emitting monochromatic light of wavelength 5500 Å?
A photometer is used to compare the illuminance of two sources. If the distances of the sources are adjusted so that their illuminance is equal, what can be said about the luminous intensities?
A photometer is used to compare the illuminance of two sources. If the distances of the sources are adjusted so that their illuminance is equal, what can be said about the luminous intensities?
What is the unit of luminous intensity?
What is the unit of luminous intensity?
What is the relationship between luminous intensity and illuminance at a point on a surface, according to the inverse square law?
What is the relationship between luminous intensity and illuminance at a point on a surface, according to the inverse square law?
What is the units of illuminance in photometry?
What is the units of illuminance in photometry?
What is the luminous efficiency of a 40 W tungsten bulb, given that its luminous flux is 465 lumen?
What is the luminous efficiency of a 40 W tungsten bulb, given that its luminous flux is 465 lumen?
If the illuminance at a point on a surface is 4 lux, what will be the illuminance at a point 2 times farther away from the source?
If the illuminance at a point on a surface is 4 lux, what will be the illuminance at a point 2 times farther away from the source?
What is the ratio of illuminance at two points on a surface, if the distance of the second point from the source is 3 times that of the first point?
What is the ratio of illuminance at two points on a surface, if the distance of the second point from the source is 3 times that of the first point?
A surface has a luminance of 20 candelas per square meter. If the luminous flux incident per unit area of the surface is 10 lumens per square meter, what is the illuminance of the surface?
A surface has a luminance of 20 candelas per square meter. If the luminous flux incident per unit area of the surface is 10 lumens per square meter, what is the illuminance of the surface?
What is the relation between the luminous intensity (L) and the illuminance (I) of a unidirectional point source of light?
What is the relation between the luminous intensity (L) and the illuminance (I) of a unidirectional point source of light?
If the luminous flux of 1 lumen is falling on an area of 1 square meter of a surface, what is the illuminance of that surface?
If the luminous flux of 1 lumen is falling on an area of 1 square meter of a surface, what is the illuminance of that surface?
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