Description : Calculate the illuminance at a surface distance 0.5m from a ligth source of luminous intensity 200 cd, assuming normal incidence. If the area of the s
Last Answer : Calculate the illuminance at a surface distance 0.5m from a ligth source of luminous intensity 200 cd, ... , what is the luminous flux on this area ?
Description : SI unit of luminous intensity is ______. (1) lumen (2) lux (3) candela (4) watt
Last Answer : (3) candela Explanation: Luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function, a ... the sensitivity of the human eye. The SI unit of luminous intensity is the candela (cd).
Description : Define the terms: (i) Lamp efficiency (ii) Luminous flux (iii) Luminaire (iv) Colour Rendering Index.
Last Answer : i) Lamp efficiency or luminous efficiency: It is the ratio of luminous flux emitted by a lamp to the power consumed by the lamp. It is a reflection of efficiency of energy conservation ... of surfaces illuminated by a given source compare to those of the same surface under reference illuminant.
Description : Candela is the basic unit of---------? A. luminous intensity (Answer) B. heat producing value C. Thermodynamic temperature
Last Answer : A. luminous intensity (Answer)
Description : Define the following terms and state their units: (i) Luminous intensity, (ii) Luminous flux
Last Answer : i) Luminous intensity: This is defined as the luminous flux emitted into a solid angle of space in a specific direction. Its unit is the candela. OR The luminous flux per unit solid angle ( ... energy radiated by the light source in all direction. The unit of luminous flux is lumen (lm)
Description : Calculate the intensity of illumination at a distance of 0.5m from a source of light of power 200 candela assuming normal incidence.
Last Answer : Calculate the intensity of illumination at a distance of 0.5m from a source of light of power 200 candela assuming normal incidence.
Description : The luminous effeciency of a lamp is `51mW^(-1)` and its luminous intensity is 35 cd. Determine the power of the lamp.
Last Answer : The luminous effeciency of a lamp is `51mW^(-1)` and its luminous intensity is 35 cd. Determine the power of the lamp.
Description : Lux is the SI unit of - (1) intensity of illumination (2) luminous efficiency (3) luminous flux (4) luminous intensity
Last Answer : (1) intensity of illumination Explanation: The SI unit of intensity of illumination (illuminance) is the lux. An illuminance of 1.0 lux is produced by 1.0 lumen of light shining on an area of 1.0 m2.
Description : Light intensity is generally described in terms of __________ and measured in _________. ∙ A. Luminous flux density; Lumens per unit area ∙ B. Luminous flux intensity; Lumens per unit area ∙ C. Luminous flux density; Lumens per unit volume ∙ D. Luminous flux intensity; Lumens per unit volume
Last Answer : Luminous flux density; Lumens per unit area
Description : The SI unit of luminous emittance is - (1) Lux (2) Candela (3) Lumen (4) Lumen second
Last Answer : (1) Lux Explanation: The lux is the SI unit of illuminance and luminous emittance, measuring luminous flux per unit area. It is equal to one lumen per square metre. In photometry, this is used as a ... of the intensity, as perceived by the human eye, of light that hits or passes through a surface.
Description : The SI unit of luminous emittance is : (1) Lux (2) Candela (3) Lumen (4) Lumen second
Last Answer : Lux
Description : A good photographic print is obtained by an exposure of 2s at a distance of 1m from a 60 candela lamp. What time of exposure must be given to get equa
Last Answer : A good photographic print is obtained by an exposure of 2s at a distance of 1m from a 60 candela lamp ... at a distance of 2m from a 200 cadela lamp ?
Description : Calculate the energy when the magnetic intensity and magnetic flux density are 15 and 65 respectively. a) 755 b) 487.5 c) 922 d) 645
Last Answer : b) 487.5
Description : Calculate the energy in an electric field with flux density 6 units and field intensity of 4 units. a) 12 b) 24 c) 36 d) 48
Last Answer : a) 12
Description : Luminous efficiency is least for a A. mercury vapor lamp B. low-wattage light bulb C. high-wattage light bulb D. fluorescent tube
Last Answer : B. low-wattage light bulb
Description : Define each of following terms of illumination — lux, lumen, luminous flux, illumination.
Last Answer : i) Lux :- It is unit of illumination and it is defined as luminous flux falling per unit area ii) Lumen: It is defined as the luminous flux emitted by a source of one candle power per unit ... the given surface on the working plane. The unit of illumination is lumens/m2 OR lumens/m2 = 1 Lux
Description : What current is required to light two 75 watt lamps and one 40 watt lamp when connected in series to a 120 volt power source? A. 0.161 amperes B. 0.631 amperes C. 1.583 amperes D. 6.199 amperes
Last Answer : Answer: C
Description : The effects due to electric current are: I. Magnetic effect II. Heating effect III. Luminous effect Application working on which effect can be used on AC as well as DC supply? a. I only b. II only c. II and III only d. I, II only
Last Answer : The effects due to electric current are: I. Magnetic effect II. Heating effect III. Luminous effect Application working on which effect can be used on AC as well as DC supply? a. I only b. II only c. II and III only d. I, II only
Description : Planets do not twinkle because they (a) emit light continuously (b) are luminous sources of light (c) are nearer to us and therefore their light does not pass through the atmosphere (d) are nearer to us and therefore minor variations in their intensity are not noticeable
Last Answer : Ans:(d)
Description : Unit of luminous intensity is A. m B. kg C. cd D. mol
Last Answer : . m
Description : The electric field intensity of a field with velocity 10m/s and flux density of 2.8 units is a) 0.28 b) 28 c) 280 d) 10/2.8
Last Answer : b) 28
Description : ECE Board Exam March 1996 A car horn outdoors produces a sound intensity level of 90 dB at 10 ft away. At this distance, what is the sound power in watt? A. 12 W B. 0.12 W C. 0.012 W D. 1.2 W
Last Answer : C. 0.012 W
Description : Can I put a 26 Watt energy saver (Equivalent to 100W) in a 60 Watt max lamp?
Last Answer : yes. It’s equivalent in how much light it gives off compared to a 100W incandescent bulb. Those get much hotter.
Description : I have a 60 watt/120v clip-on lamp. What is the highest wattage of compact fluorescent bulb can I safely use in this lamp?
Last Answer : By the way, I mean actual watts on the fluorescent bulb, not replacement-watts. :)
Description : A frosted bulb which may be taken as an isotropic source, gives as illumination of `8lm//m^(2)` at a distance of 5m. Calculate (i) its luminous intens
Last Answer : A frosted bulb which may be taken as an isotropic source, gives as illumination of `8lm//m^(2)` ... and (ii) the total luminous flux from the blub.
Description : How many lumens in a 250 Watt incandescent lamp?
Last Answer : The actual amount of light (lumens) given off by a bulb depends on the how the bulb was made and with what materials. It depends on the filament material, its length and thickness, and the ... 3940 lumens at its highest setting.Philips 250 Watt 120 to 130V PAR38 Krypton Flood Bulb emits 3100 lumens
Description : Which of the following statements is true if a 100 watt lamp and a 75 watt lamp are connected in parallel across a 100 volt power supply? A. The 75 watt lamp will draw as much current as the 100 ... Current flow will be the same across each lamp. D. The 75 watt lamp will have a higher resistance.
Last Answer : Answer: D
Description : A homeowner replaces a 65 watt incandescent bulb with a 15 watt compact fluorescent lamp. The light is on 2000 hours a year. If electricity cost 10 cents a kilowatt-hour, how much money is saved on the electric bill in one year? w) $50.00 x) $10.00 y) $5.00 z) $1.00
Last Answer : ANSWER: X -- $10.00
Description : If voltage across a bulb rated 220 volt-100 watt drops by `2.5 %` of its value, the percentage of the rated value by which the power would decrease is
Last Answer : If voltage across a bulb rated 220 volt-100 watt drops by `2.5 %` of its value, the percentage of the rated value ... 20%` B. `2.5%` C. `5%` D. `10%`
Description : A single phase wattmeter rated for 500 V; 5A is having full scale deflection of 1000 watt. What is multiplying factor of the wattmeter?
Last Answer : Answer :
Description : An electric bulb is hanging above the centre of a circular table of radiys 3m at a height of 3m from the its centre. Find the ratio of illuminance at
Last Answer : An electric bulb is hanging above the centre of a circular table of radiys 3m at a height of 3m from the ... and at a point on the edge of the table.
Description : In a TV studio the illuminance is about:
Last Answer : 1000 lux
Description : Name the quantities which are measured by the following units. (i) Newton (ii) Joule (iii) Watt (iv) Volt (v) Light year (vi) Angstrom (vii) Acre-foot (viii) Becquerel (ix) Hertz (x) Cusec
Last Answer : Answers: (i) Force (ii) Work Energy (iii) Power of electricity (iv) Potential difference (v) Distance of stars and planets (vi) Length (vii) Volume (viii) Radioactivity (ix) Frequency (x) Rate of flow of water
Description : Watt is a unit of - (1) Time (2) Power (3) Light (4) intensity of light
Last Answer : (2) Power
Description : One method of testing for a reversed shunt field coil in a DC generator or motor is by connecting the field to a direct current source, at reduced field rated voltage, and test for ... placed near each field C. test lamp across adjacent fields D. copper jumper across the interpole connections
Last Answer : Answer: B
Last Answer : "60W = 5-700 lumens. Of the links, 12W is 700 lumens, so it's about 60W."
Description : What continent is in 20s 60w?
Last Answer : on what continent would you find 20 S 60w
Description : Is peru east west of the 60'w meridian?
Last Answer : WEST
Description : Three bulbs are rating 40W 60W and 100W designed to work on 220V mains. Which bulb will burn most brightly if they are connected in series across 220 V mains? a. 40 W bulb b. 60 W blub c. 100 W blub d. all will burn equally brightly
Last Answer : a. 40 W bulb
Description : There are three bulbs of 60W 100W and 200W which bulb has thickest filament. a. 100W b. 200W c. 60W d. All
Last Answer : b. 200W
Description : Calculate the number of free electrons passing through the filament of an electric lamp in one hour when the current through the filament is 0.32 A.
Last Answer : Calculate the number of free electrons passing through the filament of an electric lamp in one hour when the current through the filament is 0.32 A.
Description : Calculate the emf of a material having a flux linkage of 2t 2 at time t = 1second. a) 2 b) 4 c) 8 d) 16
Last Answer : b) 4
Description : State the use of following: (i) Screw driver (ii) Nose pliers (iii) Wire gauge (iv) Test lamp
Last Answer : i) Screw Driver: Usually hand-operated, for turning screws with slotted heads for losing and tightening the screws. ii) Nose pliers : To hold and tight the wires iii) Wire Gauge: To ... supply voltage, Verification of voltage & current in the system and also check the open circuit fault.
Description : A lamp is hanging along the axis of a circular table of radius r. at what height should the lamp be placed above the table so that the intensity of il
Last Answer : A lamp is hanging along the axis of a circular table of radius r. at what height should the lamp be placed ... is `(1)/(8)` of that at its centre ?
Description : A ground detection system is shown in the illustration for a three-phase ungrounded distribution system. Which of the following statements describes the conditions indicated if a full ground occurs in line 'A'? EL-0009 A ... . D. Lamp 'A' will go out and Lamps 'B' and 'C' will burn brightly.
Description : Calculate the emf of a material having flux density 5sin t in an area of 0.5 units. a) 2.5 sin t b) -2.5 cos t c) -5 sin t d) 5 cos t
Last Answer : d) 5 cos t
Description : Calculate the reluctance of the material with a mmf of 3.5 units and flux of 7units. a) 32.5 b) 10.5 c) 0.5 d) 2
Last Answer : b) 10.5
Description : Calculate the flux density due to a circular conductor of radius 100nm and current 5A in air. a) 10 b) 100 c) 0.1 d) 1
Last Answer : a) 10