Home
Class 12
MATHS
The "luminous flux" or perceived brightn...

The "luminous flux" or perceived brightness, of a light source is measured in lumens and is inversely proportional to the square of the distance from the light. If a light source produce 200 lumens at a distance at a distance of 3 meters, at what distance will the light source produce a luminous flux of 25 lumens?

Text Solution

Verified by Experts

The correct Answer is:
`6sqrt(2)` meters for `sqrt(72)` meters
Promotional Banner

Similar Questions

Explore conceptually related problems

What is the shape of the wavefront diverging from a point source of light?

The intensity of light at a distance 'r' from the axis of a long cylindrical source is inversely proportional to 'r'

The distance of a star from the earth is 8.33 light minutes.' What do you mean by this statement ? Express the distance in metre.

The intensity produced by a long cylindrical light source at a small distance r from the source is proportional to

A photo cell is receiving light from a source placed at a distance of 1 m . If the same source is to be placed at a distance of 2 m , then the ejected electron

Two coherent sources are placed 0.9 mm apart and the fringes are observed one metre away. The wavelength of monochromatic light used if it produces the second dark fringes at a distance of 10 mm from the central finge will be

The height of a light house is 40 m. The angle of depression of a ship from the top of the light house is 60^(@) . Find the distance of ship from the light house.

For light diverging from a point source : a) the wavefront is spherical b) the intensity decreases in proportion to the distance squared c) the wavefront is parabolic d) the intensity at the wavefront does not depend on the distance

The distance between two coherent sources is 1 mm. The screen is placed at a distance of 1 m from the sources. If the distance of the third bright fringe is 1.2 mm from the central fringe, the wavelength of light used is

The source is at some distance from an obstacle. Distance between obstacle and the point of observation is .b. and wavelength of light is .lambda. . Then the distance of nth Fresnel Zone will be at a distance……….from the point of observation.