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A 60W lamp is rated at 0.8 watt/candela...

A 60W lamp is rated at 0.8 watt/candela. Calculate (i) luminous intensity of the lamp, (ii) luminous flux of the lamp, and (iii) illuminance at a distance of 2m from the lamp.

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75 cd, 942.8 ml, 3 lux
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Photometry: The measurement of light as perceived by human eye is called photometry. Photometry is measurement of a physiological phenomenon, being the stimulus of light as received by the human eye, transmitted by the optic nerves and analysed by the brain. The main physical quantities in photometry are (i) the luminous intensity of the source, (ii) the luminous flux or flow of light from the source and (iii) illuminance of the surface. The SI unit of luminous intensity (I) is candela (cd). The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 xx 10^12 Hz and that has a radiant intensity in that direction of 1/683 watt per steradian. If a light source emits one candela of luminous intensity into a solid angle of one steradian, the total luminous flux emitted solid angle is one lumen (1m). A standard 100 watt incandescent light bulb emits approximately 1700 lumens. A standard 100 watt incandescent light bulb emits approximately:

Photometry: The measurement of light as perceived by human eye is called photometry. Photometry is measurement of a physiological phenomenon, being the stimulus of light as received by the human eye, transmitted by the optic nerves and analysed by the brain. The main physical quantities in photometry are (i) the luminous intensity of the source, (ii) the luminous flux or flow of light from the source and (iii) illuminance of the surface. The SI unit of luminous intensity (I) is candela (cd). The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 xx 10^12 Hz and that has a radiant intensity in that direction of 1/683 watt per steradian. If a light source emits one candela of luminous intensity into a solid angle of one steradian, the total luminous flux emitted solid angle is one lumen (1m). A standa o incandescent light bulb emits approximately 1700 lumens. Unit of luminous flux is:

Photometry: The measurement of light as perceived by human eye is called photometry. Photometry is measurement of a physiological phenomenon, being the stimulus of light as received by the human eye, transmitted by the optic nerves and analysed by the brain. The main physical quantities in photometry are (i) the luminous intensity of the source, (ii) the luminous flux or flow of light from the source and (iii) illuminance of the surface. The SI unit of luminous intensity (I) is candela (cd). The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 xx 10^12 Hz and that has a radiant intensity in that direction of 1/683 watt per steradian. If a light source emits one candela of luminous intensity into a solid angle of one steradian, the total luminous flux emitted solid angle is one lumen (1m). A standa o incandescent light bulb emits approximately 1700 lumens. The SI unit of luminous intensity is:

Photometry: The measurement of light as perceived by human eye is called photometry. Photometry is measurement of a physiological phenomenon, being the stimulus of light as received by the human eye, transmitted by the optic nerves and analysed by the brain. The main physical quantities in photometry are (i) the luminous intensity of the source, (ii) the luminous flux or flow of light from the source and (iii) illuminance of the surface. The SI unit of luminous intensity (I) is candela (cd). The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 xx 10^12 Hz and that has a radiant intensity in that direction of 1/683 watt per steradian. If a light source emits one candela of luminous intensity into a solid angle of one steradian, the total luminous flux emitted solid angle is one lumen (1m). A standa o incandescent light bulb emits approximately 1700 lumens. What is photometry?

Photometry: The measurement of light as perceived by human eye is called photometry. Photometry is measurement of a physiological phenomenon, being the stimulus of light as received by the human eye, transmitted by the optic nerves and analysed by the brain. The main physical quantities in photometry are (i) the luminous intensity of the source, (ii) the luminous flux or flow of light from the source and (iii) illuminance of the surface. The SI unit of luminous intensity (I) is candela (cd). The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 xx 10^12 Hz and that has a radiant intensity in that direction of 1/683 watt per steradian. If a light source emits one candela of luminous intensity into a solid angle of one steradian, the total luminous flux emitted solid angle is one lumen (1m). A standa o incandescent light bulb emits approximately 1700 lumens. Light received by human eye is analysed by:

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.

A lamp of luminous intensity 100 cd is held at a distance of 2 m from a vertical wall. A plane mirror is fixexd on the opposite wall which is at a distance of 4 m from the lamp. Calculate the illumainance on the wall opposite to the mirror at a point on the horizontal line through the lamp. Also calculate the luminous flux on a small area or 0.02 m^(2) surrounding the point.

A converging lens is to projected image of a lamp 4 times the size of the lamp on a wall at a distance of 10m from the lamp. The focal length of the lens is

SL ARORA-RAY OPTICS-Problems For Self Practice
  1. A 60W lamp is rated at 0.8 watt/candela. Calculate (i) luminous inten...

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  2. Iluminance of 2.4 xx 10^(5)lm//m^(2) of the surface is produced by sun...

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  3. The luminous effeciency of a lamp is 51mW^(-1) and its luminous intens...

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  4. At what distance form a light source of 64 cd, will the intensity of i...

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  5. Calculate the illuminance at a surface distance 0.5m from a ligth sour...

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  6. A good photographic print is obtained by an exposure of 2s at a distan...

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  7. Two lamps of illuminating powers 25 cd and 100 cd are placed at the en...

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  8. Two light sources of intensities 8 cd and 12 cd are placed on the same...

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  9. A lamp is hanging at a height of 4 m above a table. The lamp is lowere...

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  10. In Bunsen's grease spot photometer, light from a lamp with dirty chimn...

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  11. An electric bulb illuminates a plane surface. The intensity of illumin...

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  12. A lamp is hanging along the axis of a circular table of radius r. at w...

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  13. An electric bulb is hanging above the centre of a circular table of ra...

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  14. In Fig. the circular cross-section of tunnel is shown. A 100 W almp is...

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  15. A frosted bulb which may be taken as an isotropic source, gives as ill...

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  16. A man is running away from a plane mirror at the speed of 5 ms^(-1). W...

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  17. A plane mirror rotating at an angular velocity of 3 radian/s reflects ...

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  18. A ray of light is incident at an angle of 60^(@) on a horizontal plane...

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  19. rays of light strike a horizontal plane mirror at an angle of 45^(@). ...

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  20. Two plane mirrors are inclined at angle theta as shown in figure. If a...

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