The Behavior of WavesThe Behavior of Waves

ReflectionReflection•Reflection occurs when a wave Reflection occurs when a wave

strikes an object and bounces off strikes an object and bounces off of it.of it.

•All types of wave can be reflected.All types of wave can be reflected. •Sound reflection is an echo.Sound reflection is an echo.•Light reflection in a mirror.Light reflection in a mirror.

The Law of ReflectionThe Law of Reflection• Normal – line drawn Normal – line drawn

perpendicular to the perpendicular to the surfacesurface

• The beam striking the The beam striking the mirror is called the mirror is called the incident beam.incident beam.

• The beam that bounces The beam that bounces off the mirror is called off the mirror is called the reflected beam.the reflected beam.

• Angles are measured Angles are measured between the beams between the beams and the normal.and the normal.

The Law of ReflectionThe Law of Reflection

•The angle of incidence is The angle of incidence is always equal to the angle of always equal to the angle of reflection.reflection.

RefractionRefraction• The wave speed is determined by the The wave speed is determined by the

medium. medium. • Different mediums, different speeds.Different mediums, different speeds.• Because of the difference in speeds Because of the difference in speeds

the wave will bend as it goes from the wave will bend as it goes from one medium into another.one medium into another.

Refraction Refraction • RefractionRefraction is is

the bending of a the bending of a wave caused by wave caused by a change in its a change in its speed as it speed as it moves from one moves from one medium to medium to another.another.

DiffractionDiffraction• DiffractionDiffraction the the

bending of waves bending of waves around the edge of a around the edge of a barrier.barrier.

• Diffraction and Diffraction and refraction both cause refraction both cause waves to bend. waves to bend.

• Refraction occurs Refraction occurs when waves pass when waves pass from one medium to from one medium to another.another.

• Diffraction occurs Diffraction occurs when waves pass when waves pass around an object in around an object in the same medium.the same medium.

Diffraction & WavelengthDiffraction & Wavelength• The amount of bending depends The amount of bending depends

upon the wavelength and the upon the wavelength and the opening being similar in size.opening being similar in size.

• Light won’t diffract through a Light won’t diffract through a doorway, but sound willdoorway, but sound will

Diffraction of Radio WavesDiffraction of Radio Waves• AM radio waves have longer AM radio waves have longer

wavelengths than FM radio waves.wavelengths than FM radio waves.• Therefore, AM radio waves diffract Therefore, AM radio waves diffract

around obstacles like buildings and around obstacles like buildings and mountains and FM won’t diffract as mountains and FM won’t diffract as muchmuch

• AM radio reception is often better than AM radio reception is often better than FM reception around tall buildings and FM reception around tall buildings and natural barriers such as hills.natural barriers such as hills.

InterferenceInterference• When two or more waves traveling When two or more waves traveling

through the same space at the same through the same space at the same time.time.

• They combine to form a new wave, They combine to form a new wave, the process is called the process is called interferenceinterference..

Constructive InterferenceConstructive Interference• When the two or more waves add When the two or more waves add

together to form a larger amplitude together to form a larger amplitude than either of the other waves alone.than either of the other waves alone.

• Energies add to transfer more total Energies add to transfer more total energy.energy.

Destructive InterferenceDestructive Interference• When the two or more waves add When the two or more waves add

together to form a smaller amplitude together to form a smaller amplitude than either of the other waves alone.than either of the other waves alone.

• Energies subtract to transfer less Energies subtract to transfer less total energy.total energy.

Standing WavesStanding Waves• A A standing wavestanding wave is when two waves is when two waves

equal in wavelength and amplitude, but equal in wavelength and amplitude, but traveling in opposite directions interfere traveling in opposite directions interfere with each other.with each other.

ResonanceResonance• The process by which an object is made The process by which an object is made

to vibrate at its natural frequencies is call to vibrate at its natural frequencies is call resonanceresonance..