Calculate the illuminance of the road surface

1. Lamps of 800 cd and 1200 cd are mounted 4mapart on a level surface. A vertical screen is arranged between the lamps so that its surfaces are normal to the lamps. The screen is 2.5mfrom the 800 cd lamp. Calculate the illuminance of both sides of the screen. 2.Two lamps, each of intensity 2400 cd, are mounted 6 m above a level roadway and 20 m apart. Calculate the illuminance of the road surface (a) directly beneath one lamp, (b) halfway between the points beneath the lamps and (c) 4 m from the point beneath one lamp, and between them.

 

 

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Sketch the load characteristics, terminal voltage/load current, of the following types of DC generator

1. (a) Sketch the load characteristics, terminal voltage/load current, of the following types of DC generator: (i) series-connected, (ii) shunt-connected and (iii) compound-connected.   (b) State one purpose for which….

what happens if the resistance in series with the shunt field of a DC motor is increased in value

1. Sparking at the trailing edges of the brushes in a DC machine is usually prevented by fitting   (a) copper gauze brushes (b) a compensating winding (c) a compound….

Calculate the synchronous speed of a 10-pole three-phase machine connected to a 50 Hz supply.

1. The generator characteristic shown in Figure 9.28 is for a   (a) shunt machine (b) series machine (c) differentially compounded machine (d) cumulatively compounded machine 2.The speed of a….