CHARACTERISTICS OF WAVES

LESSON ONE:

IMPORTANT VOCAB

• wave- disturbance involving a transfer in energy
• energy- ability to do work
• medium- material that a wave travels through

MECHANICAL WAVES

• Waves that require a medium
• Mechanical waves form when a source of energy causes a medium to vibrate

TYPES OF MECHANICAL WAVES:

TRANSVERSE WAVES

• A wave that vibrates a medium at a right angle or perpendicular to the direction in which the wave travels
• crest- high point in transverse wave
• trough- low point of a transverse wave

LONGITUDINALWAVES

• Vibrates the medium the same direction that the wave travels
• compression- area where coils are close together
• rarefaction- area where coils are spread out
• (view video)

SURFACE WAVES

• A combination of transverse and longitudinal waves
• Travels along a surface that separates two mediums
• Ocean waves are the most common surface waves

LESSON TWO:

AMPLITUDE

• amplitude- maximum distance the medium vibrates from the rest position
• amplitude describes how far the wave moves.
• high waves have more energy than low waves

WAVELENGTH

• wavelength- distance between two corresponding waves
• you can find wavelength of a transverse wave by measuring the distance from crest to crest

FREQUENCY

• frequency- number of waves that pass a given point in a certain amount of time
• hertz- unit that frequency is measured in.
• Hertz is defined as numbers of waves per second
• Example: a wave that occurs every second has a frequency of 1 wave per second (1/s) or 1 Hz

SPEED

• The speed of a wave is how far the wave travels in a given amount of time. You can determine a wave’s speed by dividing the distance it travels by the time it takes to travel that distance.

Speed, wavelength, and frequency of a wave are related by a mathematical formula:
Speed= wavelength x frequency
Frequency= speed/wavelength
Wavelength= speed/frequency

LESSON THREE:

Waves change direction by reflection, refraction, and diffraction. Light waves differ from water waves and sound waves because light can travel through empty space.

When a wave hits a surface, any part of the wave that cannot pass through the service bounces back. This is called a reflection.

REFRACTION

• Changes in speed can cause waves to change direction
• Light travels in a straight line except when it enters a new medium at an angle. One side of the wave changes speed before the other side. This causes the wave to bend.
• Refraction- bending of waves due to a change in speed

Bending does not occur if the wave enters at a right angle or if the speed of the wave in the new medium is the same as it was in the old medium.

DIFFRACTION

• Sometimes waves bend around barriers or pass through openings. When a wave dodges a barrier or passes through an opening in a barrier it spreads out or bends. This is called diffraction
• The sunsets appear red because of the light diffracting from dust particles in the atmosphere.

INTERFERENCE

• Interference- interaction between waves that meet
• There are two types of interferences
• Constructive interference- interference where waves combine to make a larger wave with a larger amplitude.
• Destructive interference- interference where waves combine to make a smaller wave with a smaller amplitude.

STANDING WAVES

• Standing wave- wave that appears to stand in one place even though it is two waves interfering as they pass through each other.
• If an incoming wave and reflected wave have just the right frequency, they will form a standing wave.

STANDING WAVES

• nodes- points in a standing wave that have zero amplitude and are produced by destructive interference
• antinodes- points of maximum amplitude in a standing wave

RESONANCE

• If a nearby object vibrates at the same frequency as another, it can cause resonance
• resonance- an increase in the amplitude of a vibration that occurs when external vibrations match an object’s natural frequency

THE END