# PHYSICS : REVISION TEST ON TOPICS OF CLASS XII ---III

Light from a point source falls on a small area placed perpendicular to the incident light. If the area is rotated about the incident light by an angle of 60o, by what fraction will the illuminance change?
It is doubled
It is halved
It will not change
It become one-fourth
A point source of 100 candelas is held 5m above a sheet of blotting paper which reflects 75% of light incident upon it. The illuminance of blotting paper is ____.
4 phot
4 lux
3 phot
3 lux
Two lamps of luminous intensity of 8 Cd and 32 Cd respectively are lying at a distance of 1.2 m from each other. Where a screen should be placed between two lamps such that its two faces are equally illuminated due to two sources?
10 cm from 8 Cd lamp
10 cm from 32Cd lamp
40 cm from 8 Cd lamp
40 cm from 32 Cd lamp
A lamp is hanging at a height 40 cm from the centre of a table. If its height is increased by 10 cm the illuminance on the table will decrease by ____.
10 %
20%
27%
36%
/
/
/
A point source of 3000 lumen is located at the centre of a cube of side length 2m. The flux through one side is ____.
500 lumen
600 lumen
750 lumen
1500 lumen
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TOPICS : PHOTOMETRY

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Kajal Sengupta
Physics 9th to 12 th grade,CIE, Edexcel, AP, IB , CBSE, ICSE
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