Unit 14: Waves, Sound, and Physical Optics

Waves transfer ______ between two locations.

Energy

Wave Pulse

A single disturbance that transfers energy without transferring matter

How does a wave move?

By propagating (to move through)

Mechanical Waves

Requires a medium to move through

Electromagnetic Waves

Doesn’t require a medium to move through

Longitudinal Waves

The motion of the medium is parallel to the wave

Transverve Waves

The motion of the medium is perpendicular to the wave

____________ waves only happen in mechanical waves.

Longitudinal

Parts of a Longitudinal Wave

Parts of a Transverse Wave

What does the speed of a wave depend on?

• Tension (F_T) - increasing tension increases speed

• Linear density (kg/m) - decreasing linear density increases speed

Sound waves travel fastest when in a ____ climate not a ____ climate.

Warm; Cold

Amplitude

Maximum displacement of a wave, wave pulse, or oscillation from its equilibrium position

Amplitude is based off of ________.

Pressure

The higher the amplitude, the ______ the sound in a sound wave.

Louder

The higher the amplitude, the ______ of light in a light wave.

Brighter

The speed of a wave depends on the _______.

Medium

A single point on a periodic wave moves a distance of ____ amplitudes.

Four (4)

Does amplitude affect wave speed?

No

How are energy (E) and amplitude (A) related?

E = A²

Period

Number of seconds it takes for a wave or oscillation to happen

Period (seconds) = total # of sec/# of oscillation

Frequency

Number of times a wave or oscillation happens every second

Frequency (Hertz) = total # of oscillation/# of seconds

Higher frequency means ______ periods.

Shorter

How is frequency related to pitch?

A higher frequency is equal to a higher pitch

Higher pitch means a ______ period and a _______ frequency.

Shorter; Higher

What does frequency tell us about a light wave?

Tells us what type of wave it is (or what color it is)

A greater frequency means that I have _______ energy.

Greater

Is amplitude related to the period and frequency of a wave?

No, it is completely independent

Y = Asin((2π)(X)/T)

Y = y-axis variable (pressure)

A = amplitude

sin = can be sin, cos, - sin, or -cos depending on the shape of the wave

T = period

X = x-axis variable (time)

B = Asin((2π)(X)/𝜆)

B = y-axis variable (magnetic field)

𝜆 = wavelength

X = x-axis variable (time)

Medium

A substance through which a wave may travel

When a wave travels from a low-mass string to a high-mass string, part of the wave energy is

Reflected back while some is transmitted into the new medium

Frequency of transmitted and reflected waves is the same as the rate at which

1. The wave created in the new medium is

2. The rate at which the wave would be reflected

If the wave speed decreases in the new medium, the reflected wave will be ________

Inverted

If the wave speed increases in the new medium, the reflected wave maintains its _________ __________

Original orientation

When wave speed changes so does _________

Wavelength

Nearly all light waves are ____________

Unpolarized

How does polarized light look like?

A)

When unpolarized light passes through a polarizing filter, approximately 50% of the original intensity is transmitted

How many filters do we need to completely block out light?

Two and the intensity (I) will drop to 0

Intensity

Measure of amount of power transferred per unit area

I = Power/Area or I = (Energy/Time)/Area

After a wave is polarized, _____ is decreased, which means that intensity also decreases.

Power

A polarized wave will have a lower _________.

Intensity

The speed of a wave depends on what?

The medium and type of wave moving through the medium.

What affects the wave speed of an electromagnetic wave?

It depends on the materials electric permittivity and magnetic permeability.

Electromagnetic Waves

A combination of transverse electric and magnetic waves that oscillate at right angles to each other

When a wave source is moving just as fast as the observer, the observed frequency is

equal to the rest frequency

When a wave source is moving toward an observed, the observed frequency is

Greater than the rest frequency

When a wave source is moving away from an observed frequency is

Less than the rest frequency

When a light source is moving toward a viewer, the observed color is

Shifted towards the blue end of the visible light spectrum

When a light source is moving toward a viewer, the observed color is

Shifted toward the red end of the visible light spectrum compared to the rest color

Constructive Interference

When amplitudes add together

Destructive Interference

When two waves add together to produce a wave with 0 amplitude

Beat Frequency

When two waves with slightly different frequencies interfere, they create a phenomenon

Nodes

Where the medium never moves from equilibrium

Antinodes

Points where the medium oscillates with a maximum amplitude

Diffraction

The spreading of a wave around the edges of an obstacle and through an opening