Waves

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Waves

• Waves are rhythmic disturbances that carry energy without carrying matter

Think about the ripples on the surface of a pond. The

energy carried by the ripples travels through the water. The water is made up of

water molecules.

Mechanical Waves

•Use matter to transfer energy

The matter through which a mechanical wave travels is called a medium. For ripples on a pond, the medium is water. Sound waves can travel through air, solids, liquids and other gases.

Is there sound in

space???

In a mechanical transverse wave, the wave energy causes the matter in the medium to

move up and down or back and forth at right angles to the direction the wave

travels.

A wave has peaks and valleys at regular intervals. The high points are

called crests and the low points are called troughs.

In a compressional wave, matter in

the medium moves forward

and backward in the same

direction that the wave travels.

Sound waves are

compressional waves

Electromagnetic waves are transverse waves that are

produced by the motion of electrically charged

particles. They can travel through a medium such as a solid, liquid or gas. They

can also travel through outer space or through a

vacuum.

Amplitude of a transverse wave is ½ the distance between a crest and a trough.

In a compressional wave, the amplitude is greater when the particles of the medium are squeezed closer together in each compression and spread farther apart in each rarefaction.

A wave’s amplitude is related to the energy that the wave carries.

Waves of bright light have greater amplitudes than waves

that make up dim light.

Loud sound waves have

greater amplitudes

than soft sound waves

In a transverse wave, wavelength is the distance from the top of one crest to the top of the next crest, or from the bottom of one

trough to the bottom of the next trough.

In a compressional wave, the wavelength is the distance between the center of one compression and the center of the next compression or from the center of one rarefaction to the center of the

next rarefaction.

wavelength

wavelength

The frequency of a wave is the number of wavelengths that pass a given point in

1 s. The unit is a hertz. Higher frequencies result in shorter

wavelengths.

Either the wavelength or frequency of a light wave determines the color of the

light. In a sound wave, either the wavelength or frequency determines the

pitch.

Blue light has a larger frequency and shorter wavelength than red light

Pitch is the highness or lowness of a sound.

A flute makes notes with a high pitch and a

high frequency.

A tuba makes notes with a

low pitch and a low

frequency