Reflection, Refraction, Diffraction, Interference

Objectives WWBAT…

Describe and differentiate between reflection, refraction, diffraction, and interference

Describe the change in speed or wavelength for a refracted wave based on a diagram

Predict the shape of a wave formed by interference

The 4 Types of Wave Behaviors Reflection

Refraction

Diffraction

Interference

Reflection When a wave hits a surface and rebounds off that

surface in a different direction

Frequency Wavelength Speed

Stays the same Stays the same Stays the same

Refraction A wave changes media and changes speed

Causes waves to “bend”

Material a wave is moving through

i.e. air, water, glass, etc.

Frequency Wavelength Speed

Stays the same Decrease/Increase Decrease/Increase

Refraction How can we tell which medium a wave moves faster

in?

Wavelength is longer in deep water

Wave moves faster in deep water

Refraction How can we tell which medium a wave moves faster

in?

If the wave moves slower, it will bend away from the boundary ( (towards the perpendicular).

If the wave moves faster, it will bend towards the boundary.

Refraction Example: Does the wave move faster in air or in glass?

Refraction You Try: Does the wave travel faster in air or in water?

Air

Water

Diffraction Wave passes through a slit or around a boundary

Creates a “ripple” effect

Frequency Wavelength Speed

Stays the same Stays the same Stays the same

Interference Two or more waves collide and their amplitudes add

together or cancel out

Interference Will they add or cancel?

Interference Will they add or cancel?

Interference Will they add or cancel?

Amplitudes will add if both crests align

Amplitudes will cancel if their crests and troughs align

Interference Example: Determine the resultant waveform from the

interference of Wave 1 and Wave 2.

Interference YouTry: Determine the resultant waveform from the

interference of Wave P and Wave Q.

Interference CONNECTION ALERT!

For those of you in precalculus studying sequences and series, Fourier series are a VERY important way of describing complex waveforms (like electrical signals) as a sum of interfering sinusoids