Light Flashcards
Light
the natural agent that stimulates sight and makes things visible.
Beam
a ray or shaft of light.
Ray
each of the lines in which light (and heat) may seem to stream from the sun or any luminous body, or pass through a small opening.
Energy
the property of matter and radiation which is manifest as a capacity to perform work (such as causing motion or the interaction of molecules).
Luminous
relating to light as it is perceived by the eye, rather than in terms of its actual energy.
Non-Luminous
Not capable of producing light, but can be capable of reflecting light from another source.
Speed of Light
The distance light can travel in a unit of time through a given substance. Light travels at about 186,000 miles, or 300,000 kilometers, per second.
Shadow
a dark area or shape produced by a body coming between rays of light and a surface.
Electromagnetic Spectrum
complete range of wavelengths of energy radiated as electric and magnetic fields
Radio Waves
low energy electromagnetic waves with a much lower frequency and longer wavelength than visible light
Infra-red Radiation
invisible radiation emitted by all warm objects. You feel infra-red radiation as heat.
Visible Light
very small part of the electromagnetic spectrum to which our eyes are sensitive
Ultraviolet Radiation
invisible radiation similar to light but with a slightly higher frequency and more energy
X-Rays
high-energy electromagnetic waves that can be transmitted through solids and provide information about their structure
Gamma Rays
high-energy electromagnetic radiation produced during nuclear reactions. They have no mass and travel at the speed of light.
Electromagnetic Waves
electromagnetic energy that is transmitted as moving electric and magnetic fields. There are many different types of electromagnetic energy, e.g. light, microwaves, radio waves.
Reflection
bouncing off the surface of a substance
Scattering
describes light sent in many directions by small particles within a substance
Transparent
describes a substance that allows most light to pass through it. Objects can be seen clearly through transparent substances.
Translucent
allowing light to come through imperfectly, as in frosted glass
Opaque
describes a substance that does not allow any light to pass through it
Concave
curved inwards
Convex
curved outwards
Lateral Inversion
reversed sideways
Refraction
change in the speed of light as it passes from one substance into another. It usually involves a change in direction.
Photons
a particle such as a quantum of light or electromagnetism
Pupil
Allows light into the eye. When there is dim light, our pupil becomes bigger. When there is bright light, our pupil becomes smaller.
Iris
Controls the size of the pupil and controls how much light is let in. When there is dim light, our pupil becomes bigger. When there is bright light, our pupil becomes smaller.
Lens
Focuses light onto the retina, it is transparent. There are no blood vessels.
Retina
Detects light using cells called photoreceptors
Optic Nerve
Receives signals from the retina and sends them to the brain
Sclera
Protects the eye and helps it maintain its shape
Choroid
Contains blood vessels, which bring nutrients to the eye
Cornea
Protects the front of the eye, there are no blood vessels.
Vitreous humour
Helps the eye maintain its shape
Aqueous humour
Brings nutrients to the cornea and lens, which lack blood vessels
