Bill Nye: Waves Bill Nye: Waves Waves, Sound, & Light Energy

 Wave: a disturbance that transfers energy from place to place

Wave Properties:  High point is the crest,  Low point is the trough  From rest position to crest is amplitude  From crest to crest is wavelength  The number of complete waves that pass a given point in a certain amount of time is frequency.

 Frequency is measured in hertz (Hz)  A wave that occurs every second has a frequency of 1 Hz.  Speed of the wave = wavelength x frequency. Ex: 2 cm x 2 Hz = 4cm/s  Frequency = speed ÷ wavelength Ex: 4 cm/s ÷ 2 cm = 2 Hz  Wavelength = speed ÷ frequency Ex: 4 cm/s ÷ 2 Hz = 2 cm

 Interference: the combination of waves at the same place at the same time. (constructive v. destructive)

 Sound: vibrations transmitted through a medium detectable by auditory sense organs Bill Nye: Sound Bill Nye: Sound 2:55-Brick/Metal; 6:38-Slinky/Air Hockey; 8:00-Echo; 9:30-model ear drum; 11:00-pitch; 18:10-Resonance

Echo: bouncing back of waves upon reaching a surface.

Speed of sound depends on the elasticity, density & temperature of the medium 1.increased elasticity = increased speed (snaps back to shape quickly) 2.increased density = decreased speed (molecules don’t move freely) 3.increased temperature = increased speed (molecules move more freely) In general, sound travels fastest in solids, then liquids, In general, sound travels fastest in solids, then liquids, & slowest in gases & slowest in gases

 Pitch: how high or low the frequency of a sound is (determined by frequency)  Doppler Effect: the apparent change in frequency of a wave as the source moves in relation to the observer

Decibels (dB): relative intensity of sound (determined by amplitude). Resonance: an effect in which the vibration of one object the vibration of one object causes the vibration of another object at a natural frequency. causes the vibration of another object at a natural frequency.

 Electromagnetic waves are produced when something accelerates an electric charge and requires no medium to travel in and they travel in all directions.  Electromagnetic Spectrum: the range of electromagnetic waves placed in order from longest to shortest wavelength

Visible Light: the ROYGBIV segment of the electromagnetic spectrum  Combination of all colors of light makes white light.  Color of a substance is what color(s) it reflects, it absorbs all other colors Bill Nye: Light & Color Bill Nye: Light & Color

 Transparent: a material that allows all light through. ( Example: window glass)  Translucent: a material that lets some light through, but image lacks details. ( Example: shower door) ( Example: shower door)  Opaque: a material that lets no light go through. ( Example: block wall) ( Example: block wall)

 Reflection: bouncing back of waves upon reaching another surface  Angle of Incidence = Angle of Reflection: The reflected angle is equal in degrees to the angle in which the light enters (angle of incidence). _V_ Bill Nye: Light and Optics Bill Nye: Light and Optics8:24-lenses12:53-Refraction; 17:47-Internal Reflection & Bending Light

 Refraction: Bending of waves due to a change in speed when a light goes through different mediums.  Diffraction: bending of a wave as it passes through matter with openings that separate it by wavelength.

Lenses & Mirrors  Plane – flat surface.

Lenses & Mirrors Concave – curves inward Convex – curves outward

 Origin of Light: Emission of excited electrons/radiation from atoms.  Photon: a discrete bundle (or quantum) of light energy.  Dual Nature of Light: light has properties of both a wave & a particle