Optics And Vision Exam Flashcards
Define Transparent
Describes materials that allow light to pass through with little or no reflection; for example glass
Define Opaque
Describes materials that do not allow
light to pass through; for example, wood, metal, cardboard, etc
Define Reflection
Is the changing of direction of light as it hits an opaque material
Define Umbra
The fully shaded region of a shadow
Define Penumbra
The partially shaded region of a shadow, formed by some light passing an opaque object
Define Specular Reflection
Reflection off smooth surfaces
Define Diffuse Reflection
Reflection of light off an uneven surface, which results in light scattering in many directions
Define Real Image
An image that appears on the same side of a concave mirror as the object; light rays pass through the object location and the image can be projected on to a screen
Define Virtual Image
An image that appears to be on the other side of a plane mirror; light rays do not pass through the image location
Define Refraction
Change in direction of light as it travels from one material to another
Define Visible Light Spectrum
Colours of visible light which can be seen by the eye; the colours seen in a rainbow or when light is split by a prism
Define Electromagnetic Radiation
All forms of radiated energy: visible light, infrared radiation, ultraviolet radiation, radio waves, X-rays, etc
Define Wavelength
Distance between the top or peak of one wave to the peak of the next
Define Ray
A directed straight line that represents the path followed by light
Define Illuminance
The amount of light arriving at one place per unit area
Types of Lenses (Describe)
Convex lens - curves outward, thicker in middle
Concave lens - curves inward, thicker at edges
Eye lens - focuses light on your retina so you can see a clear image
Camera lens - focuses light on your CCD matrix to illuminate pixels
General - a piece of glass/plastic light goes through
Define Retina
Special lining on the back of your eye; when light hits the retina, receptor cells send messages to the brain, which are translated into an image
Define Aperature
Hole or opening that lets light in a camera
Define Diaphragm
Part that changes the size of the aperture of camera’s lens; it varies the amount of light that reaches the film or photosensitive elements
Define Pupil
Opening in the eye that lets light in
Define CCD Matrix
A combination of Charged Coupled Device cells in a camera which has a similar function to the retina in the eye
Define Iris
Band of muscle in your eye that controls the size of the pupil and the amount of light entering your eye
Define Myopia
Nearsightedness
Define Hyperopia
Farsightedness
Define Addition Model of Colour
Theory that explains what happens when coloured lights are mixed together to produce colours
Define Subtraction Model of Colour
Theory that explains what happens when coloured pigments (paints) are mixed together; each primary colour of pigment absorbs, or subtracts, a primary colour of light and reflects the other two
Define Amplitude
Height of the wave from its middle rest position to its highest point
Define Frequency
Number of times a wave source or
medium vibrates in a given unit of time
Define Bioluminescence
Light emitted from a living organism as a result of naturally occurring chemical reactions inside the organism
Define Chemiluminescence
The production of light through a chemical reaction
Define Phosphorescence
A glow caused by the absorption and then release of stored light
Define OLED
Organic light-omitting diode. A source of electroluminescence in which the light-emitting layer is an organ ice compound
Define Electroluminescence
The emission of light as a result of an electric current being passed through a material
Define CFL
Compact Fluorescent Light. Source of artificial light; an opaque tube coated on the inside with a fluorescent material; uses ultraviolet light waves to make the fluorescent coating produce light
Define Ray Diagram
Diagram used to represent how light travels; each ray has an arrow to shoe the direction of travel
Define Shadow
Area of reduced light created whenever an opaque object blocks the path of light
Define Law of Reflection
Area of reduced light created whenever an opaque object blocks the path of light
Define Focal Point
Area of reduced light created whenever an opaque object blocks the path of light
What are the Primary Colours of Light?
Red, green, and blue light; adding these colours of light produces white light
Define Incidence
The intersection of a line, or something moving in a straight line, such as a beam of light, with a surface
Define Concave (mirror & lens)
Mirror - Reflecting surface that is curved inward like the inside of a bowl or spoon; light rays reflected from it converge or come together
Lens - Piece of transparent material that is thinner in the middle than at the edges; it diverges or spreads out light rays passing through it
Define Convex (mirror & lens)
Mirror - Outwardly-curved reflecting surface that bulges out like the back of a spoon; light rays reflected from it diverge or spread out
Lens - Piece of transparent material that is thicker in the middle that at the edges; it converges, or brings together, light rays passing through it
Properties of Light?
• Light consists of colours that can be split apart and brought back together.
• Light moves outward in every direction from a light source.
• Light is a form of energy.
• Light is something our eyes can detect.
• Light moves in straight lines.
• Light can be reflected and refracted.
• Illuminance decreases with distance from its source.
Define LCD
Liquid crystal displays (LCDs) are used every day to display information electronically on computer monitors, television screens, and instrument panels.
What is the Law of Refraction?
Angle of incidence equals angle of refraction
What are the Secondary Colours of Light?
The secondary colours of light are yellow, cyan, and magenta. Yellow is produced by mixing green and red light.
Define Cones
The retina itself is made up of specialized cells. Some of these cells are called cones. When light hits the cones they get excited, these excited cones send messages to your brain. The colour that you see depends on the type and number of cones responding to the light entering your eye.
Define Rods
Sensory cells in eyes that sense black-white & give peripheral vision
How is a shadow created?
When light hits an opaque material.
What are the different parts of a shadow?
The umbra - fully shaded
The penumbra - Some blocked, some pass
What are the three types of materials light can hit?
Transparent, opaque, translucent
What is illuminance?
The amount of light arriving at one place per unit area.
How is a luminance affected by distance?
The longer the ray goes on for, the more it will fade.
What is light pollution?
There are so many lights from lamps and buildings going to the sky, that bounce off clouds to form a glow.
What are some ways to combat light pollution?
Dark-sky preserves, nocturnal preserves.
What is the law of reflection?
Angle of incidence equals angle of reflection.
Draw a ray diagram showing the different aspects of the law of reflection including the incident ray, reflected ray, angle of incidence, angle of reflection, and mirror
Arrow pointing to mirror.
What is the difference between specular and difuse reflection?
Specular - smooth surface
Difuse-rough surface, image
What is refraction?
Light passing through one substance into another changes speeds resulting in change of direction.
What is the difference between a concave and convex lens?
Convex - focusses on a point
Concave - spreads out
How does light pass through a concave lens?
Light rays spread out.
How does light pass through a convex lens?
Light rays cross on a point.
