A reflection occurs when a wave bounces back after hitting a barrier. All wave can be reflected.
Sound waves reflecting off a barrier are called an echo.
Waves are not always reflected when they hit a barrier. Sometimes they pass through a substance. When a wave passes through a substance, it is transmitted.
Why do waves diffract?
Diffraction is the bending of waves around a barrier or through an opening. Waves usually travel in a straight line. When a wave reaches the edge of an object or an opening in a barrier, it may curve or bend.
The amount of diffraction of a wave depends on its wavelength and the size of the barrier opening.
If the barrier or opening is larger than the wavelength of the wave, there is only a small amount of diffraction
If the barrier or opening is the same size or smaller than the wavelength of an approaching wave, the amount of diffraction is large
Why do waves refract?
Refraction is the bending of a wave as the wave passes from one medium to another. The wave changes speed as it passes from one material to the other. The change in speed causes the wavelength to change.
When light waves from the sun pass through a droplet of water in the air, the light is refracted. The different colors of light travel at different speeds through the water droplet.
Relationship between Wavelength and Energy
Two waves of the same amplitude may carry more or less energy depending on its wavelength.
The wave with a shorter wavelength carries more energy than the wave with a long wavelength.
What is the Frequency of a Wave?
The frequency of a wave is the number of waves produced in a given amount of time.
Frequency is often expressed in hertz (Hz). One hertz equals one wave per second.
What is Wave Speed?
Wave speed is the speed at which a wave travels through a medium. Wave speed is symbolized by v.
The speed of a wave is a property of the medium. Changing the medium of a wave changes its speed.
The amplitude of a transverse wave is related to the height of the wave.
Amplitude is the maximum distance the particles of the wave vibrate away from their rest position.
Relationship between Amplitude and Energy
Taller wave have larger amplitudes and therefore carries more energy that a wave with a short amplitude.
What is the Wavelength of a Wave?
The wavelength is the distance between any point on a wave and the identical point on the next wave.
A wavelength is the distance between two neighboring crests or two compression(s). The distance between two troughs or two rarefactions next to each other is also a wavelength.
Relationship between Wavelength and Energy
Two waves of the same amplitude may carry more or less energy depending on its wavelength.
The wave with a shorter wavelength carries more energy than the wave with a long wavelength.
What is the Frequency of a Wave?
The frequency of a wave is the number of waves produced in a given amount of time.
Frequency is often expressed in hertz (Hz). One hertz equals one wave per second.
What is Wave Speed?
Wave speed is the speed at which a wave travels through a medium. Wave speed is symbolized by v.
The speed of a wave is a property of the medium. Changing the medium of a wave changes its speed.
The speed of sound depends on the state of the medium. Sound travels faster though solids than through liquids or gases.
The speed of sound also depends on the temperature of a medium.
How are pitch and frequency related?
The pitch of a sound is how high or low the sound seems to be. The pitch of a sound depends on the frequency of the sound wave.
The frequency of a sound wave is the number of compression or rarefaction(s) in a certain amount of time.
Frequency is often expressed in hertz (Hz). A frequency of 1 Hz is equal to 1 compression or rarefaction per second.
Frequency and Hearing
Humans, like all animals, can only hear sound with certain frequencies. Sound with frequencies too high for people to hear are called ultrasonic sounds.
The Doppler effect
The Doppler effect is a change in the pitch of a sound you hear that is caused by motion.
After the car passes, it is moving in the opposite direction from the sound waves. The compression and rarefactions of the sound wave are farther apart. The frequency of the sound seems to go down.
When the car is approaching you the compression and rarefactions of these sound waves are pushed closer together. The frequency (pitch) of the sound seems to go up.
How are Loudness and Amplitude related?
The loudness of a sound is a measure of how well the sound can be heard. A sound's loudness depends on the amplitude of a sound wave.
The larger the amplitude, the louder the sound. Conversely, the smaller the amplitude, the quieter the sound.
