# Illumination MCQ Question and Answer

### 1.Which of the following statements is correct?

• ALight is a form of heat energy
• BLight is a form of electrical energy
• CLight consists of shooting particles
• DLight consists of electromagnetic waves

Light consists of electromagnetic waves

Explanation:

### 2.Luminous efficiency of a fluorescent tube is

• A10 limens/watt
• B20 limens/watt
• C40 limens/watt
• D60 limens/watt

60 limens/watt

Explanation:

### 3.Candela is the unit of which of the following?

• AWavelength
• BLuminous intensity
• CLuminous flux
• DFrequency

Luminous intensity

Explanation:

### 4.Colour of light depends upon

• AFrequency
• BWave length
• CBoth (a) and (b)
• DSpeed of light

Both (a) and (b)

Explanation:

• ALumen meter
• BLux
• CFoot candle
• DCandela

Lux

Explanation:

• DDegrees

Explanation:

### 7.The unit of luminous flux is  ___________

• AWatt/sq. Metre
• BLumen
• CLumen/sq. Metre
• DWatt

Lumen

Explanation:

• A0.5 lagging
• B0.8 lagging
• CUnity

Unity

Explanation:

• ATungsten
• BCopper
• CCarbon
• DAluminium

Tungsten

Explanation:

### 10.Fine diameter tungsten wires are made by

• ATurning
• BSwaging
• CCompressing
• DWire drawing

Wire drawing

Explanation:

### 11.What percentage of the input energy is radiated by filament lamps?

• A2 to 5 percent
• B10 to 15 percent
• C25 to 30 percent
• D40 to 50 percent

10 to 15 percent

Explanation:

### 12.Which of the following lamps is the cheapest for the same wattage?

• AFluorescent tube
• BMercury vapour lamp
• CGLS lamp
• DSodium vapour lamp

GLS lamp

Explanation:

• A100 W
• B75 W
• C40 W
• D15 W

75 W

Explanation:

### 14.In house the illumination is in the range of

• A2 – 5 lumens/watt
• B10 – 20 lumens/watt
• C35 – 45 lumens/watt
• D60 – 65 lumens/watt

60 – 65 lumens/watt

Explanation:

### 15.“The illumination is directly proportional to the cosine of the angle made by the normal to the illuminated surface with the direction of the incident flux”. Above statement is associated with

• ALambert’s cosine law
• BPlanck’s law
• CBunsen’s law of the illumination
• DMacbeth’s law of illumination

Lambert’s cosine law

Explanation:

### 16.The colour of sodium vapour discharge lamp is

• ARed
• BPink
• CYellow
• DBluish green

Yellow

Explanation:

### 17.Carbon arc lamps are commonly used in

• APhotography
• BCinema projectors
• CDomestic lighting
• DStreet lighting

Cinema projectors

Explanation:

### 18.Desired illumination level on the working plane depends upon

• AAge group observers and Whether the object is stationary or moving
• BSize of the object to be seen and its distance from the observer
• CWhether the object is to be seen for longer duration or shorter duration of time
• DAll above factors

All above factors

Explanation:

### 19.On which of the following factors does the depreciation or maintenance factor depend?

• ALamp cleaning schedule
• BAgeing of the lamp
• CType of work carried out at the premises
• DAll of the above factors

All of the above factors

Explanation:

### 20.In lighting installation using filament lamps  1% voltage drop results into

• ANo loss of light
• B1.5 percent loss in the light output
• C3.5 percent loss in the light output
• D15 percent loss in the light output