Home
Class 12
PHYSICS
A lamp placed 70.0 cm from a screen on o...

A lamp placed 70.0 cm from a screen on one side produces the same illumination as a standard 60 cd lamp placed 105 cm away on the other side of the screen. What is the luminous intensity of the first lamp ?

Promotional Banner

Topper's Solved these Questions

  • RAY OPTICS

    SL ARORA|Exercise Problems For Self Practice|109 Videos

  • RAY OPTICS

    SL ARORA|Exercise TYPE F|10 Videos

  • RAY OPTICS

    SL ARORA|Exercise Problems|26 Videos

  • OPTICAL INSTRUMENTS

    SL ARORA|Exercise Problems for self practice|35 Videos

  • SOLIDS AND SEMICONDUCTOR DEVICES

    SL ARORA|Exercise PROBLEM_TYPE|9 Videos

Similar Questions

Explore conceptually related problems

An object placed at 20 cm from a lens, forms an image on a screen placed 60 cm on the other side of the lens. What is the focal length and type of the lens ?

An intensity of illumination of 4 flux is required at a distance of 5m from an electric lamp. What must be the luminous intensity of the lamp?

A 16 cd lamp placed at a distance of 125 cm from a screen produces the same illuminance on the screen as that produced by a bulb placed at a distance of 175 cm from the scree. If the bulb takes 0.85 A current at 110, find its efficiency.

An index pin of height 3 cm is kept at a distance of 15 cm from a convex lens of focal length 10 cm. The image is obtained on a screen placed on the other side of the lens. What is the height and nature of the image ?

Two small lamps A and B the first placed at 0.6m to the left of a translucent screen and the second placed at 1m to the right of the screen produced equal illumination on both sides of the screen. A third lamp of the same luminous intensity as that of A is kept to the left of A at a distance of 0.4m from A. By what distance the source B should be moved to produce equal illumination again ?

A needle placed 45 cm from a lens forms an image on the screen placed 90 cm on the other side of the lens. Identify the type of the lens and determine its focal length. What is the size of the image if the size of needle is 5.0 cm ?

A convex lens is placed at a distance of 40 cm from a screen. A point source is placed at a distance of 60 cm from the screen on the same side of the lens. At this position of point-source, a circular spot of light of diameter equal to the lens is formed. Show the formation of image by a ray diagram. Up to what distance the source be displaced so that its clear image can be formed on the screen?

A needle of height 5 cm placed 45 cm from a lens forms an image on a screen placed 90 cm on the other side of the lens the type of lens and its focal length are