Types of Waves

• Sound

• Water

• Earthquake

• Microwave

• String

• Radio

• Sine

• Cosine

• Visible light

• Telephone

• Slinky

• Stadium (Arena)

What is a wave?

A wave is a disturbance that travels through a medium from one location to another.

What is a medium?

A medium is a substance or material which carries a wave

Ex: slinky coils, water, air, earth

Waves and Softballs

• Similar: Energy is transferred from batter to the bat to the ball

• Different: Waves don’t transport matter

When observing a duck on a lake, why does the duck not move toward shore with the waves?

As the wave travels, the water is not transported to the shore, and the duck is resting on the water. The water wave only transports energy, not matter (in this case water).

A wave can be described as a disturbance which travels through a medium, transporting energy from one location to another without transporting matter.

One way to categorize waves is by the direction of movement of particles. Waves can be categorized into three groups using this method.

Transverse Waves

Ex: Water waves

Move perpendicular

Longitudinal Wave

Ex: Sound

Move parallel

Which types of waves can travel through solids?

Both transverse & longitudinal can!

Which type of waves can travel through liquids?

Only longitudinal waves can!

What evidence do seismologists have that leads them to believe the Earth’s core is a fluid?

Since only longitudinal waves travel through the interior of Earth, scientists have concluded that the Earth’s interior must be liquid.

Surface waves move in a circular or Clockwise pattern.

Raleigh Surface Waves

These waves move in a COUNTER clockwise pattern

Diagram of a transverse wave

What is the crest of a wave? The highest point on a wave (or the maximum positive displacement from the rest)

What is the trough of a wave? The lowest point on a wave (or the maximum negative displacement from rest)

What is the amplitude of a wave?The greatest distance from rest (surface area to the Crest)

What is wavelength?The length of one complete wave cycle (the distance between two consecutive, similar points on a wave)

What is the frequency of a wave?How often particles in the medium vibrate when a wave passes through the medium, or….

What is the frequency of a wave? (Part 2)…The number of waves that pass a certain point in a given amount of time.

What is the period of a wave?Period is the time to complete one wave cycle.

Frequency refers to how often something (a wave) happens. Period refers to the time it takes something (a wave) to happen.

What is an echo?A echo is a sound wave that is reflected, or bounces back.

Speed of an echo

340 m/s2

170 meters x 2

Speed of a Wave =

Wavelength ÷ Periodor

Wavelength x Frequency

How is a sound wave created?A sound wave is created by a vibrating object.

Through what medium does sound usually travel?Air, but sound can travel through anything else… steel, water, etc.

What type of wave is a sound wave? Why?Sound is a mechanical wave, which means it requires a medium through which to travel…

What type of wave is a sound wave? Why? (Part 2)… As opposed to an electromagnetic wave, which does not need a medium (ex: light)…

What type of wave is a sound wave? Why? (Part 3)… Sound is also classified as a longitudinal wave because the energy from the sound waves compresses the medium as it travels.

Other Terms to Know

• Refraction: A waves bends to a change of speed (ex. Light moving into thicker glass)

• Compression: in a longitudinal wave the place where there are MORE particles

• Rarefaction: in a longitudinal wave the place where there are LESS particles

• Incident ray: when a wave is reflected: this is the ORIGINAL wave

• Reflected ray: when a wave bounces back this is the result

FINI