CHAPTER-4

ILLUMINATION

• Q1: Define Illumination.
  Ans:Illumination means the amount of light that falls on a surface. It tells us how bright an area is. It is measured in lux or lumens per square meter.
• Q2: Define Light.
  Ans:Light is a form of electromagnetic radiation that is visible to the human eye and is essential for vision and illumination.
• Q3: Define Luminous flux.
  Ans:Luminous flux is the total amount of visible light emitted by a source per unit of time, measured in lumens (lm).
• Q4: Define Lumen.
  Ans:A lumen is a unit that measures how much light is given off by a source.
• Q5: Define Plane Angle.
  Ans:A plane angle is the angle between two lines on a flat surface. It is measured in degrees and radians.
• Q6: Define Solid Angle.
  Ans:A solid angle is the space inside a cone or 3D shape that comes out from a point. It’s measured in steradians.
• Q7: Define Steradian.
  Ans:A steradian is a unit used to measure solid angles in 3D, just like degrees are used for flat angles.
• Q8: Explain Candle Power.
  Ans:Candle power means how strong the light is in one direction. Now, it is called candela.
• Q9: What is the luminous intensity reduction factor?
  Ans:The luminous intensity reduction factor shows how light becomes less bright because of distance, dust, or old lamps.
• Q10: Define Glare.
  Ans:Glare is a very bright light that makes it hard to see and hurts your eyes.
• Q11: Define Lamp efficiency.
  Ans:Lamp efficiency tells us how much light a lamp gives compared to the electricity it uses.
• Q12: Define Reflection factor.
  Ans:Reflection factor shows how much light a surface reflects. A white wall reflects more light than a black one.
• Q13: Define Solar Geometry.
  Ans:Solar geometry is the study of the sun’s path in the sky. It helps us design buildings to get more sunlight.
• Q14: What is the Summer Solstice?
  Ans:Summer solstice is the longest day of the year, around June 21, when the sun is highest in the sky.
• Q15: What is the Winter Solstice?
  Ans:Winter solstice is the shortest day of the year, around December 21, when the sun is lowest in the sky.
• Q16: Define Equinox.
  Ans:Equinox is the time when day and night are the same length, around March 21 and September 23.
• Q17: Define Vernal Equinox.
  Ans:Vernal Equinox happens around March 21. It is the first day of spring when day and night are equal.
• Q18: Define Solar noon.
  Ans:Solar noon is the time when the sun is highest in the sky, usually around 12 p.m.
• Q19: Define Azimuth.
  Ans:Azimuth is the direction of the sun in the sky, measured from the north in degrees.
• Q20: Define Daylight.
  Ans:Daylight is the natural light provided by the sun during the daytime, used for visibility and illumination without artificial sources.
• Q21: Write the types of daylighting.
  Ans:The types of daylighting are:

  • ➔ Side Lighting
  • ➔ Top Lighting
  • ➔ Atrium Lighting
  • ➔ Light Shelf Lighting
  • ➔ Skylight
• Q22: Define Passive Daylighting.
  Ans:Passive daylighting uses the building’s design (like windows and skylights) to bring sunlight inside without using machines.
• Q23: Define Active Daylighting.
  Ans:Active daylighting uses devices like mirrors or light tubes to bring and spread sunlight into buildings.
• Q24: What are the elements of Passive Daylighting?
  Ans:The elements are:

  • ➔ Windows
  • ➔ Clerestories
  • ➔ Skylights
  • ➔ Light shelves
  • ➔ Atriums
  • ➔ Reflective surfaces
• Q25: What are the elements of Active Daylighting?
  Ans:The elements are:

  • ➔ Moving mirrors
  • ➔ Light pipes
  • ➔ Optical fibers
  • ➔ Prismatic panels
• Q26: What are the elements of Remote Distribution?
  Ans:The elements are:

  • ➔ Light guides (fiber optics or pipes)
  • ➔ Collectors
  • ➔ Distributors (diffusers or lenses)
• Q27: What are Light reflectors and shelves?
  Ans:Light reflectors and shelves bounce sunlight deeper into the room and help spread natural light evenly.
• Q28: What is the purpose of Light Tubes?
  Ans:Light tubes carry sunlight from the roof to inside rooms using reflective pipes.
• Q29: Define Artificial Lighting.
  Ans:Artificial lighting means light made by sources other than the sun like lamps, bulbs, or other electric lights.
• Q30: Write the types of Artificial Lighting?
  Ans:Following are the types of Artificial Lighting:

  • ➔ General lighting (for whole room)
  • ➔ Task lighting (for specific work)
  • ➔ Accent lighting (for decoration)
  • ➔ Decorative lighting
• Q31: Write the sources of Artificial Lighting?
  Ans:Following are the sources of Artificial Lighting:

  • ➔ Incandescent bulbs
  • ➔ Fluorescent lamps
  • ➔ LED lights
  • ➔ Halogen lamps
  • ➔ HID lamps
• Q32: Define Fluorescence.
  Ans:Fluorescence is light given off by some materials when they absorb light or energy. It's used in tube lights.
• Q33: Define Efflorescence.
  Ans:Efflorescence is the white powder seen on walls when water leaves behind salt as it dries.
• Q34: Define Incandescence.
  Ans:Incandescence is light produced when something is heated until it glows, like the wire in a bulb.
• Q35: Define Incandescents.
  Ans:Incandescents are old-style bulbs that give light by heating a wire inside.
• Q36: Define Filament.
  Ans:A filament is a thin wire inside a bulb that glows when electricity passes through it.
• Q37: What is a filament made of?
  Ans:Filaments are usually made of tungsten because it doesn’t melt easily.
• Q38: Define LED.
  Ans:An LED (Light Emitting Diode) is a small light that uses very little electricity and lasts a long time.
• Q39: Enlist the types of lamps.
  Ans:The types of lamps include:

  • ➔ Incandescent lamps
  • ➔ Fluorescent lamps
  • ➔ LED lamps
  • ➔ Halogen lamps
  • ➔ Metal halide lamps
  • ➔ Sodium vapor lamps
• Q40: Enlist lighting schemes.
  Ans:Different lighting schemes include:

  • ➔ Direct lighting (all light goes down)
  • ➔ Indirect lighting (light bounces off ceiling)
  • ➔ Semi-direct (most light down, some up)
  • ➔ Semi-indirect (most light up, some down)
  • ➔ General lighting (evenly spread light)
• Q41: What are Halogen lamps?
  Ans:Halogen lamps are a type of bulb that gives bright light and lasts longer than normal bulbs.
• Q42: Enlist the factors affecting lighting schemes.
  Ans:Following are the factors affecting the lighting scheme:

  • ➔ What the room is used for
  • ➔ Wall and ceiling colors
  • ➔ Size and shape of the room
  • ➔ Type of lights used
  • ➔ Cleaning and maintenance
• Q43: Define Lamp Angle Beam.
  Ans:Lamp Angle Beam is the angle that shows how wide the light spreads from the lamp.
• Q44: Define Depreciation Factor.
  Ans:Depreciation Factor tells how the light becomes less over time because of dirt or old lamps.
• Q45: Define Co-efficient of Utilization.
  Ans:Co-efficient of Utilization shows how much of the light from a lamp actually reaches the area we want to light.
• Q46: What is the analysis objective in a lighting scheme?
  Ans:The goal of the lighting scheme is to give enough and even light for work, safety, and comfort.
• Q47: Define Latitude.
  Ans:Latitude is the distance of a place north or south of the equator, measured in degrees. It affects sunlight and climate.
• Q48: Define Atrium.
  Ans:An atrium is an open space in the middle of a building that brings in light and fresh air.
• Q49: How are verandahs helpful in building?
  Ans:Verandahs give shade, reduce heat, and protect from rain. They also allow fresh air and natural light.
• Q50: Define Lux.
  Ans:Lux is a unit that measures how bright a surface is. One lux equals one lumen per square meter.