Invisible Waves

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Invisible Waves by Mind Map: Invisible Waves

1. Energy Transfer & Wave Basics

1.1. Basics

1.1.1. Definition: Waves transfer energy and involve oscillations, or vibrations. They transfer energy without a net motion of the medium through which they travel. Rays indicate the direction of energy transfer Waves involve compressions and rarefractions Frequency = Oscillations per second, measured in Hertz (Hz). E.G. 50 HZ means 50 vibrations per second.

1.1.2. Two Types Longitudinal (Compression) Wave: Oscillations Parallel to Direction of Energy Transfer Sound Earthquakes Transverse Waves: Oscillations are Perpendicular to Direction of Energy Transfer Water Ripples Light

1.1.3. Wavelength = Distance Between 2 Peaks or two Troughs

1.1.4. Amplitude = Maximum Distance Travelled from Undisturbed Position

1.1.5. Peak (Crest) = "High" Point of Wave

1.1.6. Trough = "Low" Point of Wave

1.1.7. Calculations: Wave Speed Velocity = Frequency x Wavelength Frequency = Velocity / Wavelength Wavelength = Velocity / Frequency Wave Period (Seconds per Wave) Time Period (Seconds) = Frequency (Hertz)^ -1 OR 1 / Frequency (Hertz) Example: 50 Hz = 0.02 Seconds per wave Example: 400Hz = 0.0025 Seconds per wave

1.2. Heat

1.2.1. Conduction

1.2.2. Convection

1.2.3. Radiation

1.3. Sound

1.3.1. Longitudinal (Compression Wave)

1.3.2. Higher Amplitude = Louder Volume

1.3.3. Lower Amplitude = Softer Volume

1.3.4. Longer Wavelength, Slower Frequency = Lower Pitch

1.3.5. Shorter Wavelength, Faster Frequency = Higher Pitch

1.3.6. Speed of sound in air = 330 metres per second

2. Visible Light & Colour

2.1. Overview

2.1.1. Transverse Wave

2.1.2. If something generates light, it is luminous. Otherwise, it's non-luminous.

2.1.3. Light waves travel in straight lines

2.1.4. Speed of light = 300,000,000 metres per second

2.1.5. 1 Light Year = Distance travelled by light in a year, used for astronomical objects

2.1.6. Wavelength and Frequency affect colour

2.1.7. Amplitude affects brightness, or intensity

2.2. Ray Diagrams

2.2.1. Mirrors are represented by short diagonal lines underneath mirrored surface

2.2.2. The incident ray is the light ray hitting a surface

2.2.3. The reflected ray it the light ray reflected from a surface

2.2.4. All angles are measured from the normal, which is a dotted line perpendicular to the surface the light ray hits

2.2.5. Angle of incidence = Angle from the incident ray to the normal

2.2.6. Angle of reflection = Angle from the reflected ray to the normal

2.2.7. Ray direction is indicated by small arrows on light ray

2.3. Reflection

2.3.1. Overview When light hits an object, it either passes through, gets absorbed or is reflected. Angle of Incidence = Angle of Reflection

2.3.2. Mirrors Plane Flat mirror Planar surface Curved Shape Contour?

2.4. Refraction

2.4.1. Overview The bending of light rays as they enter different mediums Part of a light ray hits a more dense medium, slowing down, and then shortly afterwards the rest of the ray hits and also slows down. This results in a change in the light ray's direction. This can also occur as rays enter less dense mediums.

2.4.2. Lenses All Lense Types True Concave: ) | Bi Concave: ) ( True Convex: ( | Bi Convex ( ) Concave vs Convex Concave = Rays diverge Convex = Rays converge Glasses Long-sighted people need convex lenses Short-sighted people need concave lenses

2.4.3. Prisms White light enters and disperses into rainbow light ROY G BIV Light disperses because red refracts less and violet refracts more, "spreading the ray out"

2.5. Sight

2.5.1. Eyes Light hits the cornea which refracts it. It then enters the eye through the pupil and is refracted even more by the flexible lense behind the pupil. The lense is stretched by ciliary muscles and is held by suspensory ligmaents. Light then hits the retina and is transferred by the optic nerve to the brain. Light refracts differently for different distances so that the focal point is always on the retina.

2.5.2. Vision Light hits an object, and all colours except for the colour of the object are absorbed. Then, the colour of the object is reflected. This reflected light then reaches our eyes. Red objects, for example, absorb all light except red light, and then reflect red light. Short vs Long Sight Short sighted people have oblong (0 ) eyeballs and fat lenses. The focal point of the light is often before the retina. Long sighted people have "thin" (0 ) eyeballs and thin lenses, and the focal point of light is often after the retina. Colours Primary Secondary Filters Filters absorb all light except the colour that they are, which passes through. Examples: