Light Fundamentals Quiz
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Questions and Answers

What is the unit of measurement for illuminance?

  • Candela per square meter
  • Watts per square meter
  • Lux (correct)
  • Lumens per square meter

Which term describes the luminous intensity emitted by a light source per unit area?

  • Illuminance
  • Luminance (correct)
  • Luminous flux
  • Optical control

How is luminous flux that is visible to the human eye described?

  • Radiant flux
  • Luminous flux (correct)
  • Lux
  • Candela

What does reflection refer to in the context of light?

<p>The process by which light leaves a medium (A)</p> Signup and view all the answers

What is the correct definition of illuminance?

<p>Luminous flux per area (C)</p> Signup and view all the answers

Which unit is used to measure luminance?

<p>Candela per square meter (B)</p> Signup and view all the answers

What might optical control include?

<p>Modifying the path of light (A)</p> Signup and view all the answers

Which of these is NOT a characteristic of luminous flux?

<p>It always remains constant regardless of conditions (C)</p> Signup and view all the answers

What is the primary function of light as defined in the fundamentals?

<p>To create a visual sensation by exciting the human retina (B)</p> Signup and view all the answers

What is radiant flux?

<p>The total power emitted or received by electromagnetic radiation (A)</p> Signup and view all the answers

What is the wavelength range associated with visible light?

<p>380 - 780 nm (B)</p> Signup and view all the answers

How is luminous flux defined?

<p>A unit of measure termed the lumen (A)</p> Signup and view all the answers

What is the relationship between radiant flux and electromagnetic radiation?

<p>Radiant flux encompasses all wavelengths of electromagnetic radiation (B)</p> Signup and view all the answers

What unit is used to measure radiant flux?

<p>Watt (C)</p> Signup and view all the answers

Which of the following statements about light is true?

<p>Light encompasses all visible and non-visible wavelengths (A)</p> Signup and view all the answers

What is the significance of the wavelength range of light?

<p>It determines the color of light perceived by humans (D)</p> Signup and view all the answers

What type of reflection occurs on a polished surface?

<p>Specular reflection (A)</p> Signup and view all the answers

Which term describes light reflecting off a rough surface?

<p>Diffuse reflection (A)</p> Signup and view all the answers

What is the outcome when parallel rays are reflected off a non-smooth surface?

<p>They spread into a cone of rays (B)</p> Signup and view all the answers

In the context of reflectance factors, which color typically has the highest reflectance?

<p>White (C)</p> Signup and view all the answers

Which combination of reflection components characterizes a compound reflector?

<p>All three: specular, spread, and diffuse (C)</p> Signup and view all the answers

What phenomenon occurs when light changes speed upon entering a different material?

<p>Refraction (B)</p> Signup and view all the answers

Which color has a reflective factor of 10-20%?

<p>Black (B)</p> Signup and view all the answers

If a material reflects radiation equally in all directions, which type of reflection is it exhibiting?

<p>Diffuse reflection (B)</p> Signup and view all the answers

What is the main characteristic of light behaving non-selectively when reflected?

<p>It reflects all incident light (A)</p> Signup and view all the answers

In terms of reflection, what does a corrugated surface primarily create?

<p>Spreading light uniformly (C)</p> Signup and view all the answers

How does the density of a medium affect the speed of light traveling through it?

<p>Speed increases in less dense media (D)</p> Signup and view all the answers

What is the reflectance percentage of lacquer, brilliant white?

<p>87-88% (C)</p> Signup and view all the answers

Which material has the lowest reflectance percentage?

<p>Concrete, dark (A)</p> Signup and view all the answers

What phenomenon occurs when light passes by an obstruction, creating an indistinct shadow?

<p>Diffraction (C)</p> Signup and view all the answers

What does diffusion refer to in the context of light?

<p>The scattering of light in many directions (A)</p> Signup and view all the answers

Which of the following materials reflects light at 60-80%?

<p>Sound Absorbing Ceiling, white (A)</p> Signup and view all the answers

When does interference occur with light waves?

<p>When they come together at different phases of their vibration (A)</p> Signup and view all the answers

What can cause a light beam to spread in many directions?

<p>Irregular reflection and refraction (C)</p> Signup and view all the answers

Which surface material has a reflectance percentage between 30-50%?

<p>Wood, light (D)</p> Signup and view all the answers

What is the reflectance percentage range of aluminium, high-gloss?

<p>75-87% (D)</p> Signup and view all the answers

Flashcards

Radiant Flux

The measurable quantity of light that can be detected by the human eye.

Luminous Flux

The measure of radiant flux per unit area.

Illuminance

Illuminance is the amount of luminous flux falling on a unit area.

Luminance

The luminous intensity emitted by a light source per unit area.

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Units of Illuminance

Measured in lux, which is equivalent to lumens per square metre.

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Units of Luminance

Measured in candela per square metre.

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Optical Control

Optical control refers to various phenomena that manipulate light direction and intensity.

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Reflection

Reflection occurs when light bounces off a surface, changing its direction.

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What is light?

Light is a form of radiant energy that can be seen by humans because it stimulates the retina in our eyes.

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Visible Spectrum

The range of electromagnetic radiation that the human eye can detect.

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Lumen

The unit of luminous flux, representing the amount of light emitted in one direction by a standard light source.

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Visible Light Range

The wavelengths of electromagnetic radiation that are visible to the human eye, ranging from approximately 380 to 780 nanometers.

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Standard Light Source

A standard light source used to define the lumen, often a special tungsten filament lamp.

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Specular Reflection

Light bouncing off a smooth surface, with the angle of incidence equaling the angle of reflection.

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Diffuse Reflection

A surface reflects light in a wide range of directions, resulting in a blurry or scattered reflection.

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Compound Reflection

A combination of specular, spread, and diffuse reflection, creating a complex reflection pattern.

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Reflectance

The proportion of light reflected from a surface. A higher reflectance means more light is reflected.

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Surface Color

The color of a surface is determined by the wavelengths of light it reflects.

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Spread Reflector

A reflector that reflects light in a wide range of directions, creating a spread of reflected light.

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Diffuse Reflector

A reflector with a rough surface that reflects light in multiple directions, creating a diffuse reflection.

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Selective Reflection

When the reflected light from a surface is filtered or absorbed, resulting in selective color reflection.

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Nonselective Reflection

A reflector that reflects all wavelengths of light equally, resulting in a white or neutral reflection.

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Speed of Light in Different Media

The change in the speed of light when it moves from one medium to another. It's faster in less dense mediums like air and slower in denser mediums like water.

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Interference

The interaction of two light waves of the same wavelength, resulting in a combined wave with an amplitude between the difference and sum of the original waves, depending on their relative phase.

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Diffraction

The bending of light waves around an obstacle. This causes the light to spread out and create a blurry, indistinct shadow.

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Diffusion

The breaking up of a light beam into multiple directions due to scattering by microscopic particles or irregularities in a medium.

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Scattering

The process of light interacting with particles or molecules in a medium, leading to a change in direction of the light, resulting in a scattered beam. This is a key factor in diffusion.

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Absorption

The ability of a surface to absorb light energy. Darker surfaces absorb more light than lighter surfaces.

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Study Notes

Light Fundamentals

  • Light is radiant energy that creates visual sensation in humans
  • Light is defined by its relative efficiency across the electromagnetic spectrum, approximately 380-780 nm
  • Radiant flux is the total power of electromagnetic radiation (measured in watts)

Radiant Flux

  • Radiant flux is the term for the total power of electromagnetic radiation
  • Measured in watts

Luminous Flux

  • Luminous flux is the radiant flux of light detectable by the human eye.
  • Measured in lumens

Illuminance

  • Illuminance (symbol E) is the amount of luminous flux falling on a unit area of a surface.
  • Measured in lux (lumens per square meter)

Luminance

  • Luminance (symbol L) shows the luminous intensity per unit area of a light source
  • Measured in candela per square meter

Optical Control

  • Optical control involves several phenomena: reflection, refraction, interference, diffraction, diffusion, and absorption

Reflection

  • Reflection is the process where light bounces off a surface.
  • Can be specular (smooth surfaces) or diffuse (rough surfaces)

Reflection & Reflectors

  • Specular reflection occurs when a smooth surface reflects light rays at a predictable angle.
  • On a rough surface the rays of light spread out in many different directions; this is called diffuse reflection

Spread

  • Spread reflection occurs when a surface is not smooth.
  • The reflected rays spread out instead of all reflecting at the same angle.

Diffraction

  • Diffraction is the bending of light as it passes through or around an obstacle.
  • Creates an indistinct or blurred shadow

Diffusion

  • Diffusion involves light spreading out in different directions
  • Caused by irregular reflections and refractions from tiny particles, droplets, or bubbles

Absorption

  • Absorption occurs when light energy is absorbed by a material and is not transmitted or reflected.
  • The material may become warmer due to the absorbed energy.

Refraction & Refractors

  • Refraction is the bending of light when it passes from one medium to another of different optical density.
  • The change in speed depends on the density of the medium

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Related Documents

Lighting Fundamentals PDF

Description

Test your knowledge on the fundamentals of light, including concepts like radiant flux, luminous flux, illuminance, and luminance. This quiz covers essential definitions and measurements related to light and optical control phenomena such as reflection and refraction.

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