Waves

Electromagnetic Spectrum Range of electromagnetic radiation or light Range of electromagnetic radiation or light Amount of energy given off by atomic electrons Amount of energy given off by atomic electrons Visible Light – middle of spectrum Visible Light – middle of spectrum ROY G BIV ROY G BIV

Electromagnetic Spectrum

Waves Rhythmic disturbances that transmit Rhythmic disturbances that transmit Energy Energy Information Information Waves are usually comprised of a Waves are usually comprised of a higher-energy state followed by a higher-energy state followed by a lower-energy state lower-energy state of a medium or an energy field of a medium or an energy field

Two kinds of waves Classified by the motion of the medium compared to the motion of the wave Classified by the motion of the medium compared to the motion of the wave ACTUAL MEDIUM PARTICLES DO NOT MOVE!!! ACTUAL MEDIUM PARTICLES DO NOT MOVE!!!

Two Kinds of Waves Transverse (Sine) Waves Transverse (Sine) Waves Medium particles move at right angles to the wave direction Medium particles move at right angles to the wave direction Water waves, wind waves, EM waves (radio, light, X-Rays, etc.) Water waves, wind waves, EM waves (radio, light, X-Rays, etc.)

Two kinds of waves Longitudinal (Compression) Waves Longitudinal (Compression) Waves Medium particles move in the same direction as the wave Medium particles move in the same direction as the wave Sound waves, certain earthquake waves, springs Sound waves, certain earthquake waves, springs

Which kind of wave vibrates in the same direction as the wave? 1. Transverse Wave 2. Longitudinal Wave 3. Seismic Wave 4. Big Kahuna Wave

Which of these can be transmitted by a wave? 1. Energy 2. Information 3. Particles 4. None of these

What name is given to the material through which a wave travels? 1. Water 2. Air 3. Steel 4. Medium

Which kind of wave vibrates at right angles to the wave? 1. Transverse Wave 2. Longitudinal Wave 3. Seismic Wave 4. Big Kahuna Wave

A wave is a 1. Motion on the ocean 2. Amber unit of grain 3. Non-verbal good-bye signal 4. Rhythmic disturbance

Which of these is an example of Compression or Longitudinal waves? 1. Sound Waves 2. Water Waves 3. “The Wave” at Quest Field 4. None of these

Which of these is an example of Transverse waves? 1. Sound Waves 2. Cymbals 3. Accordions 4. Ultraviolet Light

PARTS OF A TRANSVERSE WAVE

Parts of a Transverse Wave The Normal or Rest Position The Normal or Rest Position Represents the “undisturbed” medium Represents the “undisturbed” medium Crest Crest Point representing the highest energy of the wave Point representing the highest energy of the wave Trough Trough Point representing the lowest energy of the wave Point representing the lowest energy of the wave

Properties of a Transverse Wave Amplitude Amplitude Distance from the normal or rest position to the crest or trough Distance from the normal or rest position to the crest or trough “Height” of the wave “Height” of the wave Represents the amount of energy in the wave Represents the amount of energy in the wave Wavelength Wavelength Distance from one point on the wave to the same point on the next wave Distance from one point on the wave to the same point on the next wave Distance of ONE FULL CYCLE of the wave Distance of ONE FULL CYCLE of the wave Frequency Frequency Number of waves that pass a point in a unit of time Number of waves that pass a point in a unit of time Measured in Hertz (Hz) for waves per second Measured in Hertz (Hz) for waves per second

Parts of a Longitudinal Wave The Normal or Rest Position The Normal or Rest Position Represents the “undisturbed” medium Represents the “undisturbed” medium Compression Compression Area representing the highest energy of the wave Area representing the highest energy of the wave Medium particles are pressed together, area of high energy Medium particles are pressed together, area of high energy Rarefaction Rarefaction Area representing the lowest energy of the wave Area representing the lowest energy of the wave Medium particles are far apart, area of low energy Medium particles are far apart, area of low energy

Properties of a Longitudinal Wave Amplitude Amplitude How “tightly compressed” particles of the wave are How “tightly compressed” particles of the wave are Represents the amount of energy in the wave Represents the amount of energy in the wave Wavelength Wavelength Distance from one point on the wave to the same point on the next wave Distance from one point on the wave to the same point on the next wave Distance of ONE FULL CYCLE of the wave Distance of ONE FULL CYCLE of the wave Frequency Frequency Number of waves that pass a point in a unit of time Number of waves that pass a point in a unit of time Measured in Hertz (Hz) for waves per second Measured in Hertz (Hz) for waves per second

Longitudinal Waves Areas where the lines are close together is the same as the CREST in a transverse wave. Areas where the lines are close together is the same as the CREST in a transverse wave.

Wave is the WORD! Decibel – unit of sound intensity Decibel – unit of sound intensity Ultrasonic – above 20,000 hertz Ultrasonic – above 20,000 hertz Echolocation – using reflected waves to judge the size, shape, or location of an object Echolocation – using reflected waves to judge the size, shape, or location of an object Supersonic – faster than the speed of sound Supersonic – faster than the speed of sound Vibration – cause of sound Vibration – cause of sound

What is the lowest energy area of a longitudinal wave called? 1. Compression 2. Medium 3. Wavelength 4. Rarefaction

What is the highest point of a transverse wave called? 1. Trough 2. Amplitude 3. Crest 4. Rest

What is the lowest point of a transverse wave called? 1. Trough 2. Amplitude 3. Crest 4. Rest

Which describes how often a wave point passes a particular location? 1. Compression 2. Frequency 3. Wavelength 4. Amplitude

What is the horizontal line that represents an undisturbed medium? 1. Trough 2. Amplitude 3. Crest 4. Rest

What is the highest energy area of a longitudinal wave called? 1. Compression 2. Medium 3. Wavelength 4. Rarefaction

Which of these represents the amount of energy in a wave? 1. Trough 2. Amplitude 3. Crest 4. Rest

What is the distance between one point of a wave to the same point on the next wave? 1. Compression 2. Medium 3. Wavelength 4. Rarefaction

Other Wave Properties Wavespeed Wavespeed Velocity of a wave Velocity of a wave Can depend on the medium Can depend on the medium Sound travels faster through dense mediums, radio waves can’t penetrate rock Sound travels faster through dense mediums, radio waves can’t penetrate rock Wavespeed = wavelength x frequency  = x ƒ  = x ƒ Wavespeed is usually in m/s when wavelength is in m and frequency is in Hz (1/s)

More on Wavespeed All EM waves travel at the Speed of Light All EM waves travel at the Speed of Light Symbol: c Symbol: c Value: 186,282.6 miles per second Value: 186,282.6 miles per second 299,792,458 m/s 299,792,458 m/s This is currently the fastest speed in the Universe This is currently the fastest speed in the Universe

Watch for these conversions! 1m = nm (nanometers) 1nm = 1.0 x m Light vibrates in the nm and ångström ranges 1 m = Å 1 Å = 1.0 x m