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Illumination-2000 ReviewerReviewer, Reviewer, Reviewer,Reviewer,Reviewer,Reviewer Reviewer
Electronic Circuit: devices and analysis (ECDA 223)
STI West Negros University
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MULTIVECTOR REVIEW AND TRAINING CENTER
ILLUMINATION
REE - April 2006
A lamp gives an average output of 628 lumens. What is its M.S.C.? A. 50 Cd B. 40 Cd C. 45 Cd D. 48 Cd
A lamp has luminous intensity of 250 Cd. Calculate the total luminous flux emitted by it. A. 1,000 lm B. 785 lm C. 3,142 lm D. 2,000 lm
REE - Sept. 2004 3. A light source has an illumination of 100 footcandles (fc), what is the illumination in lux? A. 1,204 B. 1,075 C. 1,496 D. 1,
REE - Sept. 2004 4. A light source which radiates light in all directions has luminous intensity of 100 candela. What is the illumination E in footcandles in a perpendicular working area 10 ft distance below the source? A. 2 B. 3 C. 1 D. 2.
REE - Sept. 2006 5. A certain light source produces an illumination of 800 lux on a surface. Find the illumination on that surface if the distance to the light is doubled. A. 300 lux B. 100 lux C. 400 lux D. 200 lux
- A lamp giving 200 candles uniformly below the horizontal plane is suspended 3 m above a horizontal plane. Calculate the illumination at a point on the plane i. directly below the lamp A. 66 lm/m 2 B. 6 lm/m 2 C. 22 lm/m 2 D. 2 lm/m 2
REE - Sept. 2005 ii. 3 m away from the vertical axis A. 7 lux B. 7 lux C. 7 lux D. 7 lux
REE - Sept. 2005 7. An intensity of 100 candle power is directed at a point 10 ft distance from the source. If the receiving plane is tilted through 30 degrees from the perpendicular, what is the illumination upon the surface? A. 0 fc B. 0 fc C. 0 fc D. 0 fc
REE - April 2005 8. A 150 candlepower lamps gives sufficient light to read a book at a distance of 6 feet. If the lamp depreciates to 75 candlepower, how much closer should the book be placed to be read with same luminance in ft? A. 3 B. 2 C. 2 D. 1.
An incandescent lamp having a luminous flux of 3,000 lumens is enclosed in a 0 meter diameter diffusing sphere and having an absorption factor of 15%. Calculate the average luminance of the sphere. A. 450 B. 9,020 C. 2,255 D. 3,
Two lamp posts are 13 m apart and are fitted with 1,000 Cd lamp each at a height of 5 m above the ground. Calculate the illumination on the ground. i. under each lamp A. 41 lux B. 40 lux C. 80 lux D. 20 lux
ii. midway between the lamps A. 37 lux B. 9 lux C. 18 lux D. 27 lux
What must be the candle power of a point source of light which gives an illumination of 100 lm/m 2 at a point A 2 m vertically below the source? A. 200 Cd B. 400 Cd C. 100 Cd D. 300 Cd
In Prob. # 11, if a plane mirror which reflects 75% of the light falling on it is placed horizontally 30 cm above the source, what will be the illumination at A? A. 100 lux B. 200 lux C. 44 lux D. 144 lux
Two lamps A and B produce equal illumination on the screen of a photometer when A is 60 cm and B is 50 cm from the screen. A plane mirror is placed 6 cm behind B, the plane of the mirror being at right angles to the line from B to the screen and it is then found that to restore equality of illumination on the screen, the source A must be moved 10 cm nearer the screen. What is the reflecting power of the mirror? A. 68% B. 50% C. 62% D. 65%
After a balance was obtained between two lamps on a photometric bench, a sheet of plane glass was interposed on one side of the photometer. To restore the balance, one of the lamps was moved back through 10 cm making its distance from the photometer 110 cm. What percentage of light incident on the glass was transmitted by it? A. 90% B. 82% C. 86% D. 88%
A drawing office containing a number of boards having a total effective area of 70 m 2 is lit by a number of 40 W incandescent lamps giving 11 lm/W. An illumination of 72 lm/m 2 is required on the drawing boards. Assuming that 60% of the total light emitted by the lamps is available for illuminating the drawing boards, estimate the number of lamps required. A. 19 B. 21 C. 23 D. 25
REE - April 2004 16. A room with dimensions of 72 ft × 36 ft × 13 ft requires 50 footcandles, maintenance factor of 0, coefficient of utilization of 0 and RI of 4. Calculate the required lumens output of the lamps. A. 144,000 B. 136,800 C. 402,485 D. 74,
SUPPLEMENTARY PROBLEMS
Four lamps are suspended 8 m above the ground at the corners of a square of 3 m side. Each lamp gives 250 candelas uniformly below the horizontal plane. Calculate the illumination at the center of the square. A. 14 lm/m 2 B. 7 lm/m 2 C. 3 lm/m 2 D. 10 lm/m 2
A 100 candela lamp emits light uniformly in all directions and is suspended 2 m above the center of a working table which is 3 m square. Calculate the illumination at each corner of the table. A. 23 lux B. 8 lux C. 11 lux D. 4 lux
A work room 33 m long by 13 m wide is illuminated by means of 10 lamps suspended 3 m above the working plane. Determine the mean spherical candle power of the lamps required to give an average illumination of 27 lm/m 2 at the work table. Assume that 25% of the total light falls on the working plane. A. 369 candelas B. 318 candelas C. 398 candelas D. 400 candelas
A building 25 m long and 18 m wide is to have a minimum illumination of 56 lm/m 2. Electric lamps of efficiency 10 lm/W are to be suspended 3 m above the floor, the space/height ratio being 1. If coefficient of utilization is 0 and maintenance factor is 0, calculate the number of fittings required and the rating of each fitting in watts. A. 35,150 W B. 40,132 W C. 50,105 W D. 60,088 W
A school classroom with a general dimensions of 24 ft × 30 ft is lighted with 10 fluorescent fixtures of 4 lamps per fixture and 3,200 lumens per lamp. What is the initial illumination in footcandles assuming that coefficient of utilization is 0? A. 178 B. 44,800 C. 15,680 D. 62.
In Prob. # 5, what is the maintained illumination assuming that maintenance factor is 0? A. 43 fc B. 88 fc C. 30 fc D. 124 fc
A workshop measures 7 m × 13 m and is lighted by 10 lamps which are each rated at 200 W and have an efficiency of 15 lm/W. Assuming a depreciation factor of 1 and a coefficient of utilization of 0, find the illumination on the working plane. A. 102 lm/m 2 B. 106 lm/m 2 C. 110 lm/m 2 D. 114 lm/m 2
An office, 17 m by 8 m wide, is lighted by 8 lamps and each lamp has a luminous intensity of 200 Cd. Allowing an absorption loss of 4,000 lm for the reflectors, walls, and ceiling, calculate the average illumination on the working plane. A. 177 lm/m 2 B. 136 lm/m 2 C 118 lm/m 2 D. 152 lm/m 2
A 40-watt fluorescent lamp 120 centimeters long produces 3,200 lumens of light in a room having a general dimensions of 10 ft × 20 ft. Find the illumination on the floor. A. 640,000 fc B. 16 fc C. 160 fc D. 320 fc
In Prob. # 9, find the luminance if the reflectance factor of the wall is 40%. A. 40 footlamberts B. 102 footlamberts C. 6 footlamberts D. 2 footlamberts
REE - Sept. 2001
- The illumination of a room is being designed. The illumination intensity required is 50 footcandles. The maintenance factor is 70% and coefficient of utilization is 0. If the room is 20 ft by 15 ft, what is the total required lumens output of the lamp? A. 35,000 lumens B. 10,500 lumens C. 6,300 lumens D. 12,800 lumens
REE - April 2005 12. A room 20 ft × 30 ft is illuminated by five 200 watt, 3,700 lumen incandescent lamps. The average illumination intensity at the working plane as measured by a foot-candle meter is 10 lumens per square foot. Calculate the utilization factor of the lamps. A. 0 B. 0 C. 0 D. 0.
- At what distance from a screen should the lamp of 120 Cd be placed to produced the same illumination on the screen as a lamp of 30 Cd would give when placed at a distance of 40cm from the screen? A. 20 cm B. 40 cm C. 60 cm D. 80 cm
Illumination-2000 ReviewerReviewer, Reviewer, Reviewer,Reviewer,Reviewer,Reviewer Reviewer
Course: Electronic Circuit: devices and analysis (ECDA 223)
University: STI West Negros University
