Lights and Optics
Vocabulary
Umbra: is the fully shaded part of the shadow.
Penumbra: is the partially shaded part of the shadow.
Opaque: material that reflects or absorbs all light that reaches them
Transparent: material that allows all light to pass through.
Translucent: Material that allows some light to pass through.
Illuminance: is the amount of light spread over a specific area.
Specular Reflection: when light reflects off a smooth surface. (mirror, metal, calm water)
Diffuse Reflection: when light reflects off a rough surface. (ocean water)
Angle of Incidence: the angle between the incoming ray and the normal
Angle of Reflection: the angle between the reflected ray and the normal
Normal: a line perpendicular to the mirror
Law of Reflection: ∠i =∠r (angle of incidence is equal to the angle angle of reflection.
Rectilinear Propagation: Light travels in a straight line when in the same medium.
Convex Mirrors: in which the reflected surface is curved outwards.
Concave Mirrors: in which the reflecting surface is curved inward like a bowl.
Convex Lens: A transparent glass or plastic lens that is thicker in the middle than at the edges, which brings light rays together.
Concave Lens: A transparent glass or plastic lens that is thinner in the middle than at the edges, which spreads light rays apart.
Refraction: when light changes direction from passing from one substance to another.
Refractive Index: is a measure of how much the speed of light is reduced in a material.
Cornea: The transparent front part of the eye that focuses light and protects the eye's interior
Pupil: The opening that controls the amount of light entering the eye
Iris: The colored part that controls the size of the pupil to regulate light intake
Lens (Eye): A transparent structure that focuses light rays onto the retina
Ciliary Muscles: Muscles that change the shape of the lens to focus light on objects at different distances
Sclera: The white, tough outer layer that provides structural support and protection to the eye
Retina: The light-sensitive layer at the back of the eye containing photoreceptors (rods and cones) that detect light and convert it into electrical signals
Optic Nerve: The nerve that transmits visual signals (electrical impulses) from the retina to the brain for processing
Radio Waves:Low energy waves with the longest wavelength.
Microwaves: Only the radio waves are longer.
Infrared Radiation: Invisible electromagnetic waves that are detected as heat.
Visible Light: The portion of the electromagnetic spectrum that human eyes can detect. (ROY G BIV)
Ultra Violet Light: Higher energy than light waves.
X Rays: High energy waves
Gamma Rays: Highest energy. Blocked by the Earth’s surface by the atmosphere.
Additive Colour Model: Adding colours to create other colours.
Subtractive Colour Model: Pigments mix to create new colours.
Primary Colours: The 3 colours that our cones can detect. (Red, Green and Blue)
Secondary Colours: When two primary colours are mixed. (Cyan, Yellow and Magenta)
Complementary Colour: Any two colours of light when mixed together produce white.
Pigment: A chemical that absorbs certain colours of light but reflects others. (Cyan, Magenta and Yellow)