Electrical Illumination Fill In The Blanks

 FILL IN THE BLANKS

1. Visible light has wavelength between 4000 A and 7500 A.

2. Human eye is most sensitive for a wave length of 5500.

3. The color corresponding to wavelength 5500 A is Yellow, Green. 

4. Lamp efficiency is expressed in Lumens per watt.

Electric Illumination are true (T) or false (F)

TRUE AND FALSE

1. Carbon arc lamps needs frequent adjustment and replacement of carbon rod.--T

2. Lumen method takes into account the inter-reflections of light inside a room.--T

3. Luminairs are generally categorized as industrial, commercial or residential.--T

4. Lenses with prismatic patterns refract light sources to disperse the rays or to direct them most effectively.--T

Multiple Choice Questions of Electric Illumination

MCQ of Illumination

1. Radiant efficiency of the luminous source depends on
(A) shape of the source
(B) temperature of the source
(C) wavelength of light rays
(D) all of the above.

2. Light waves travel with a velocity of
(A) 3 x 10¹⁰cm/s
(B) 3 x 10¹²cm/s
(C) 3 x 10¹⁵ cm/s
(D) 3 x 10¹⁸ cm/s

Illumination Engineering

Electrical Illumination Definitions

Light

it is defined as the radiant energy from a hot body which produce the visual sensation upon human eye. It is usually denoted by Q, expressed in lumen-hours and is analogous to watt-hours.

Luminous Flux(F or Ф)

It is defined as the total quantity of light energy per second from a luminous body.It is represented by symbol F or Ф and unit is lumen.

Approximate relation between lumen and electric unit of power i.e. watt is given as

 1lumen=0.0016 watt(approx).

MCB or Miniature Circuit Breaker

What is MCB?

 it is device which protect conductor or electrical installation from short circuit or overload. Now-a-day instead of fusethey are used both residential and industrical wiring.These can be single pole, double pole or triple pole. It sustained overloading of 150% or above.

Electrical Basic Units

   ⚡Electrical Basic Units⚡

The standard units of electrical measurement used for the expression of voltage, current and resistance are the Volt [ V ], Ampere [ A ] and Ohm [ Ω ] respectively.

 Electrical Units & Symbols

QUANTITY	SYMBOL	UNIT	SYMBOL
Capacitance	C	Farad	F
Charge	Q	Coulomb	C
Conductance	G	Siemens	S
Current	I	Ampere	A
Energy	W	Joule	J
Frequency	f	Hertz	Hz
Impedence	Z	Ohm	Ω
Inductance	L	Henry	H
Power	P	Watt	W
Reactance	X	Ohm	Ω
Resistance	R	Ohm	Ω
Voltage	V	Volt	V

The Basic Electrical Quantities and Their Units
Potential Difference:
It is defined as the difference of electric potential between the two points in an electric circuit.
Its symbol is V and the unit of measurement is volts.
The instrument used to measure the potential difference is called as Voltmeter. The voltmeter is always connected in parallel with the circuit whose voltage is to be calculated.

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