Home
Class 12
PHYSICS
Figure shows a small diffused plane sour...

Figure shows a small diffused plane source S placed over a horizontal table-top at a distance of 2.4 m with its plane parallel to the table-top. The illuminance at the point A directly below the source is 25 lux. Find the illuminance at a point B of the table at a distance of 1.8 m from A.

Text Solution

Verified by Experts

The correct Answer is:
A
Promotional Banner

Topper's Solved these Questions

  • PHOTOMETRY

    HC VERMA|Exercise Objective 2|4 Videos

  • PHOTO ELECTRIC EFFECT AND WAVE PARTICLE DUALITY

    HC VERMA|Exercise Exercise|2 Videos

  • SEMICONDUCTOR AND SEMICONDUCTOR DEVICES

    HC VERMA|Exercise Exercises|35 Videos

Similar Questions

Explore conceptually related problems

A ladder is placed againt a wall such that its foot remains at a distance of 2.5 m from the wa and its top reaches a window 6 m above the ground. Find the length of the ladder in cm.

A ladder is placed against a wall such that its foot is at a distance of 2.5 cm from the wall and its top reaches a window 6 m above the ground. Find the length of the ladder.

Figure shows an equiconvex lens (of refractive index 1.50) in contact with a liquid layer on top of a plane mirror. A small needle with its tip on the principal axis is moved along the axis until its inverted image is found at the position of the needle. The distance of the needle from the lens is measured to be 45.0 cm. The liquid is removed and the experiment is repeated. The new distance is measured to be 30.0 cm. What is the refractive index of the liquid ?

From a point P on the ground the angle of elevation of the top of a 10m tail building is 30^(@) . A flag is hoisted at the top of the building and the angle of elevation of the top of the flagstaff from P is 45^(@) . Find the length of the flagstaff and the distance of the building from the point P. (You may take sqrt3= 1.732 )

A fixed thermally conducting cylinder has a radius R and height L_0 . The cylinder is open at its bottom and has a small hole at its top. A piston of mass M is held at a distance L from the top surface, as shown in the figure. The atmospheric pressure is P_0 . While the piston is at a distance 2L from the top, the hole at the top is sealed. The piston is then released, to a position where it can stay in equilibrium. In this condition, the distance of the piston from the top is

A quarter cylinder of radius R and refractive index 1.5 is placed on a table.A point object P is kept at a distance of mR from it. Find the value of m for whicha ray from P will emerge parallel to the table as shown in the figure.

The childern are trying to shoot a marble into a marble into a small box using a spring loaded gun that fixed on a table and shoots horizontally from the edge of the table. The centre of the box is a horizontal distance 5m from the edge of the table. The first child compresses the spring a distance 2cm and finds that the marble falls short of its target by a horizontal distance 3m . By what distance x should the second child compress the spring to score a direct hit on the box?

Two identical glass rods S_(1) and S_(2) (refractive index=1.5) have one convex end of radius of curvature 10 cm. They are placed with the curved surfaces at a distance d as shown in the figure, with their axes (shown by the dashed line) aligned. When a point source of light P is placed inside rod S_(1) on its axis at a distance of 50 cm from the curved face, the light rays emenating from it are found to be parallel to the axis inside S_(2) . The distance d is

A fixed thermally conducting cylinder has a radius R and height L_0 . The cylinder is open at the bottom and has a small hole at its top. A piston of mass M is held at a distance L from the top surface, as shown in the figure. The atmospheric pressure is P_0 . The piston is now pulled out slowly and held at a distance 2L from the top. The pressure in the cylinder between its top and the piston will then be

Quarter part of a transparent cylinder ABC of radius R is kept on a horizontal floor and a horizontal beam of light falls on the cylinder in the two different arrangement of cylinder as shown in figure (a) & (b) . In arrangement (a) light converges at point D , which is at a distance 2R/m from B. And in arrangement (b) light converges at point E, which is at a distance R/(m-1) from C. Find out the refractive index of the material.