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Questions and Answers
Which phenomenon of light can be explained using both wave and particle theories?
Which of the following is an example of electromagnetic radiation with the longest wavelength?
What is the term for the bending of light as it passes from one medium to another?
Which of the following electromagnetic radiations has the highest frequency?
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What is the phenomenon in which light is absorbed by a material, resulting in the emission of electrons?
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Which of the following types of electromagnetic radiation is used in microwave ovens?
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What is the term for the spreading of light as it passes through a narrow opening or around a corner?
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Which of the following is NOT a phenomenon that can be explained using wave theory?
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What is the term for the change in direction of light as it passes from one medium to another?
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Which of the following electromagnetic radiations has the longest frequency?
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What is the term for the relative brightness of a colour?
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What is the result of mixing all primary additive colours?
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What is the term for the colourfulness of an area relative to its brightness?
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What are the primary subtractive colours?
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What is the term for the colourfulness relative to the brightness?
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What is the result of mixing all primary subtractive colours?
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What is the term for the property of a colour that is often referred to as its 'colourfulness'?
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What is the term for the actual colour of an object or light?
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What is the term for the overall brightness of a colour?
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What are the primary additive colours?
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What is the assumption made about the surface in Lambert's Cosine law of illumination?
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What happens to illuminance when the light source is not perpendicular to the task surface?
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What is luminance a measure of?
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What is the relationship between luminous flux and luminance?
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What is the unit of measurement for luminance?
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What is the purpose of a cosine corrector in illumination?
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What is the effect of the angle of incidence on the illuminance of a surface?
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What is the relationship between luminous intensity and luminance?
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What is the unit of measurement for luminous intensity?
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What is the difference between luminous flux and luminous intensity?
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What is the direction of light at a position 50 cm to the left of the image point?
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What is the unit of measurement of the vergence L?
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What is the purpose of converting distances to meters in vergence calculations?
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What is the value of the vergence L at a position 50 cm to the left of the image point?
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What is the purpose of considering the direction of light in vergence calculations?
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What is the relationship between the position of the image point and the direction of light?
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What is the significance of the 50 cm distance in the vergence calculation?
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What is the formula used to calculate the vergence L?
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What is the unit of measurement of the distance used in the vergence calculation?
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What is the assumption made about the light in the vergence calculation?
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What is the term for the phenomenon where an image appears inverted and reversed?
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What is the purpose of the object space?
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What is the term for the distance between the object and the lens?
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What is the purpose of the lens?
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What is the relationship between the object and the image?
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What is the significance of the object distance?
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What is the purpose of the pinhole?
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What is the relationship between the lens and the image?
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What is the purpose of the object?
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What is the significance of the image?
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What is the purpose of the object space in the context of image formation?
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What is the term for the distance between the object and the lens?
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What is the purpose of the pinhole in the context of image formation?
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What is the relationship between the object and the image?
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What is the significance of the object distance in the context of image formation?
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What is the purpose of the lens in the context of image formation?
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What is the relationship between the lens and the image?
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What is the term for the phenomenon where an image appears inverted and reversed?
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What is the purpose of the object in the context of image formation?
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What is the significance of the pinhole in the context of image formation?
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Study Notes
Introduction to Optics
- The University of Western Australia acknowledges the Noongar people as the spiritual and cultural custodians of their land.
Nature of Light
- Light is an electromagnetic wave and a particle (photon).
- The dual nature of light can be demonstrated through various experiments, including the double-slit experiment.
Applications of Light
- Light has various applications in life, including:
- Telecommunications
- Manufacturing
- Renewable energies
- Lighting
- Arts
- Bio-medicine
International Day of Light
- The International Day of Light is a global initiative to appreciate the role of light in science, culture, art, education, and sustainable development.
Optometry
- Optometry is the healthcare profession that provides comprehensive primary eye care, examining the eye for defects and faults, prescribing correctional lenses, diagnosing diseases, and treating or referring for treatment.
Electromagnetic Spectrum
- The electromagnetic spectrum includes:
- Radio waves
- Microwaves
- Infrared (IR) light
- Visible light
- Ultraviolet (UV) light
- X-rays
- Gamma rays
Historical Contributions
- Thomas Young demonstrated the wave nature of light through the double-slit experiment.
- James Clerk Maxwell developed Maxwell's equations, which describe light as an electromagnetic wave.
- Albert Einstein proposed that light can behave as particles (photons).
Light Characteristics
- Light is a form of energy made up of tiny photons, each containing a lot of energy.
- Light travels faster than anything else in the universe, at a speed of 300,000 km per second in a vacuum.
Refraction
- Light usually travels on a straight path, but it bends – or refracts – when traveling through a transparent object.
- A prism is a good example of refracted light.
Light-Matter Interaction
- Light can travel through some types of matter but not others.
- Light travels through the air and can be seen through a glass window or a clear plastic wrap.
- Some objects are translucent, meaning light passes through them, while some light is reflected.
- Opaque matter reflects light or bounces it back into the environment.
Electromagnetic (EM) Wave
- Electromagnetic wave has oscillations in the electric and magnetic fields.
- EM waves may have many forms, from radio waves to X-rays, differing in frequency.
Monochromatic and Polychromatic Light
- Monochromatic light consists theoretically of a single wavelength.
- Polychromatic light consists of many wavelengths.
Colour
- Light is part of the EM spectrum, and the human eye perceives it as different colours.
- Colour is characterized by hue, colourfulness, brightness, chroma, lightness, and saturation.
Colour Mixing
- Primary additive colours are Red, Green, and Blue (RGB), and mixing all additive primaries produces white.
- Primary subtractive colours are Cyan, Magenta, and Yellow, and mixing all subtractive primaries produces black.
Introduction to Quantum Optics and Photometry
- The University of Western Australia acknowledges that its campus is situated on Noongar land, and that Noongar people remain the spiritual and cultural custodians of their land.
Quantum Optics
- Black body: ↑74*AHRXTR.
- Photons and dual nature of light: ↑ETART2D** 7 EVE.
- Photoelectric effect and quantum theory: ZET.
Atomic Structure
- Atomic structure: TFEx H discovered by 19005.
Light and Its Properties
- What is light?: a) ah 7**.
- Light intensity: LIGHT INTENSITY, LUMINANCE, LUMINOUS FLUX, and ILLUMINANCE.
Filters
- Types of filters: Neutral density (ND) filters, and filters that remove specific wavelengths (coloured filters).
- Examples of coloured filters: Shortpass edge filters and others.
Radiometry and Photometry
- Radiometry measures the radiant energy produced by an electromagnetic source, including all wavelengths, not just visible light.
- Photometry measures the perceived brightness of light by the human eye.
- Spectral luminous efficiency function of the human eye.
Radiant Power and Luminous Power
- Radiant power or flux (Ï•E): measures the total power of electromagnetic radiation emitted, reflected, transmitted, or received, per unit time, in Watts (Joules/s).
- Luminous power: measures the amount of light that is perceived by the human eye.
Illumination
- Lambert's Cosine law of illumination: illuminance (EV) is reduced by the cosine of the angle with perpendicular (q) when the light source is not perpendicular to the task surface.
- Cosine corrector: used to correct for the reduction in illuminance due to the angle of incidence.
Summary
- Luminance: a measure of the amount of luminous flux falling on a surface per unit area.
- Flux: measuring the amount of light available to illuminate an area.
Vergence and Wavefronts
- Vergence is an expression of the wavefront curvature, describing light as converging or diverging.
- The sign of the vergence depends on the geometry with respect to the direction of light propagation.
- Vergence is positive in converging rays, negative in diverging rays, and zero in parallel (flat) rays.
- The unit of vergence is the Dioptre (D), which is the reciprocal of the meter.
Converging Wavefronts
- Converging wavefronts have concentric circles increasing their curvature (vergence) as light propagates, until forming a point image at their center.
Vergence and Propagation
- The value of the vergence changes as the wavefront propagates, becoming more negative closer to the source, with a shorter distance from the source.
Plane Wavefronts
- Plane wavefronts have a radius of infinity, curvature of zero, and an image at optical infinity.
- Plane wavefronts can be observed really far away from the source, with an optical system.
Sign Convention for Wavefronts/Vergence
- Light travels from left to right, with the direction of light propagation assumed to be from left to right.
Vergence Calculation
- Vergence (L) can be calculated using the formula L = 1/d, where d is the distance from the point source or image point.
- A negative vergence value indicates diverging light, while a positive value indicates converging light.
- Distances must be converted to meters before engaging in calculations involving vergence or optical power.
Light Sources
- A light source is an object that emits light
- Primary light sources create their own light, while secondary light sources reflect light from a primary source
- Examples of light sources include people, candles, and surfaces that reflect light
Point Sources and Extended Sources
- A point source is an object that appears as a single point, emitting light in all directions
- An extended source is an object that has a larger dimension, emitting light from multiple points
- The 5 times rule states that the distance from an optical system to a light source should be greater than 5 times the largest dimension of the source for it to be called a point source
Aperture and Pinhole Camera
- A smaller aperture results in a smaller pencil of rays, resulting in a clearer image
- A pinhole camera uses a small aperture to project an inverted image onto a screen
- The pinhole acts as a point source, creating a smaller blur circle and a clearer image
Pinhole Camera and Image Formation
- The pinhole camera uses the principle of rectilinear propagation of light to form an image
- The distance between the object and the pinhole is called the object distance (l), and the distance between the pinhole and the image is called the image distance (l')
- The height of the object (y) and the height of the image (y') are related to each other and the distances l and l'
Vision and Eye Defects
- Myopia (short-sightedness) and hyperopia (long-sightedness) are two common eye defects
- Blurred images in the eye can be caused by these defects, resulting in an inability to form a sharp image on the retina
- The pinhole effect can be used to make the image at the retina sharper in ametropic eyes
Principles of Optics: Object, Images, and Blur
Primary and Secondary Light Sources
- Primary light sources emit light, e.g., the sun
- Secondary light sources reflect or transmit light, e.g., the moon
Point Sources and Extended Sources
- Point source: a small source of light, e.g., a star
- Extended source: a large source of light, e.g., a LED strip
- 5 times rule: the distance from an optical system to the light source should be greater than 5 times the largest dimension of the source/object for it to be called a point source
Blur Circles
- Blur circle: the circle of least confusion, where the image is clearest
- Smaller blur circle, clearer the image
Extended Images and Blur
- Convergent refractive surface/lens/optical system forms an image
- Extended image: an image that covers a large area
- Blur circles and pinhole camera: can have a sharp image without a converging optical system
Blur in the Eye
- Blurred images in the eye: when the eye's optical system cannot focus light directly on the retina
- Ametropia: a condition where the eye's optical system cannot focus light directly on the retina
- Emmetropia: perfect or near-perfect vision, where light converges on the retina, resulting in a sharp image
Pinhole Effect
- Pinhole effect: a small aperture can create a sharp image, e.g., pinhole glasses
- Important concepts related to objects and images:
- Object space: the area in front of the lens
- Object distance (l)
- Image space: the area behind the lens
- Image distance (l')
- Magnification: the ratio of image size to object size
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Description
Introduction to the principles of optics, covering the nature of light and acknowledgement of Noongar land and people.
