A source emits 31.4 W of radiant flux di...

A source emits 31.4 W of radiant flux distributed uniformly in all directions. The luminous efficiency is 60 lumen watt. What is the luminous intensity of the source ?

Text Solution

Verified by Experts

The correct Answer is:

A, C, D

Radiant flux `=31.4W, solid angle =4pi` Luminous efficiency =60 lumne/W So, Luminous flux =`60xx31.4` lumen and luminous intensity
`=(Luminous Flux)/(4pi)`
`=(60xx(31.4))/(4pi)`
`=150 candela`

Topper's Solved these Questions

PHOTO ELECTRIC EFFECT AND WAVE PARTICLE DUALITY
HC VERMA|Exercise Exercise|35 Videos
SEMICONDUCTOR AND SEMICONDUCTOR DEVICES
HC VERMA|Exercise exercises|35 Videos

Similar Questions

Explore conceptually related problems

What is the luminous flux of a source emitting radio waves ?

A source emits 45 joules of energy in 15 s. What is the radiant flux of the source ?

A point source emitting light uniformly in all directions is placed 60 cm above a table-top. The illuminance at a point on the table-top, directly below the source, is 15 lux. Find the illuminance at a point on the table-top 80 cm away from the first point.

A circular area of radius 1.0 cm is placed at a distance of 2.0 m from a point source. The source emits light uniformly in al directions. The line joining the source to the center of the area is normal to the area. It is found that 2.0xx1^-3 lumen of luminous flux is incident on the area. Calculate the total luminous flux emitted by the source and the luminous intensity of the source along the axis of the area.

A point source emitting uniformly in all directions is placed above a table top at a distance of 0.50 m from it. The luminous flux of the source is 500 lumen. Find the illuminance at a small surface area of the table to a.directly below the source and b. at as distance of 0.80 m from the source.

A source of sound operates at 2.0 kHz, 20 W emitting sound uniformly in all direction. The speed of sound in air is 340 m s^(-1) at a distance of air is 1.2kgm ^(-3) What is the intensity at a distance of 6.0 m from the source ?

A point source emitting 628 lumen of luminous flux uniformly in all directions is placed at the origin. Calculate the illuminance on a small area placed at (1.0 m, 0, 0) in such a way that the normal to the area makes an angle of 37^@ with the X-axis.

Find the luminous flux of 10 W source of 600 nm. The relative luminosity at 600 nm is 0.6.

A point source emits sound equally in all direction is a non-absorbing medium. Two points p and Q are at distances of 2m and 3m, respectively, from the source. The ratio of the intensities of the waves at P and Q is

The overall luminous efficient of a 100 W electric lamp is 25 lumen W^-1 . Assume that light is emitted by the lamp only in the forward half, and is uniformly distributed in al diredctionsin this half. Calculate the luminous flux falling on a plane object of area 1cm^2 placed at a distance of 50 cm from the lamp and perpendicular to the line joining the lamp and the object.

HC VERMA-PHOTOMETRY-All Questions

The brightnes producing capacity of a source
Text Solution
|
A room illuminated by an extended source. The iluminance at a particul...
Text Solution
|
Mark the correct options
Text Solution
|
Mart out the correct options
Text Solution
|
A source emits 45 joules of energy in 15 s. What is the radiant flux o...
Text Solution
|
A photographic plate records sufficient intense lines when it is expos...
Text Solution
|
Using figure 22.1, find the relative luminosity of wavelength (a) 480 ...
Text Solution
|
The relative luminosity of wavelength 600 nm is 0.6. Find the radiant ...
Text Solution
|
The luminous flux of a monochromatic source of 1 W is 450 lumen W^-1. ...
Text Solution
|
A source emits light of wavelengths 555 nm and 600 nm. The radiant flu...
Text Solution
|
A light source emits monochromatic light of wavelength 555 nm. The sou...
Text Solution
|
A source emits 31.4 W of radiant flux distributed uniformly in all dir...
Text Solution
|
A point source emitting 628 lumen of luminous flux uniformly in all di...
Text Solution
|
The illuminance of a small area changes from 900 lumen m^-2 to 400 lu...
Text Solution
|
A point source emitting light uniformly in all directions is placed 60...
Text Solution
|
Light from a point source falls on a small area placed perpendicular t...
Text Solution
|
A student is studying a book placed near the edge of a circular table ...
Text Solution
|
Figure shows a small diffused plane source S placed over a horizontal ...
Text Solution
|
An electric lamp and a candle produce equal illuminance at a photomete...
Text Solution
|
Two light sources of intensities 8 cd and 12 cd are placed on the same...
Text Solution
|