Waves

What is the relationship between frequency and wavelength?

When the medium does not change, if the frequency increases, the wavelength decreases (inverse relationship), because the speed stays the same.

Standing wave

When two interfereing waves cancel each other out.

Constructive Interference

When waves overlap in-phase (crest meets crest or trough meets trough) the waves energy is additive and the amplitude increases.

Destructive Interference

When waves overlap out-of-phase (crest meets trough) the waves cancel and the amplitude (energy) decreases.

Wave

a disturbance that transfers energy through matter or space.

Nodes

no amplitude, destructive interference Points with no displacement

Why you can't hear an explosion in outer space.

Because sound waves require particles to collide to transfer energy.

How a mechanical wave is formed.

formed by a force that creates a vibration of particles in the medium (push or pull). Example: Rock dropped into water. Plucking a guitar string.

Answer (D.) four times larger than

3. Two waves are traveling through a container of an inert gas. Wave A has an amplitude of 0.1 cm. Wave B has an amplitude of 0.2 cm. The energy transported by wave B must be __________ the energy transported by wave A. a. one-fourth b. one-half c. two times larger than d. four times larger than

The Speed Mechanical Waves travel through mediums

A mechanical wave travels faster in a solid where particles are closest together or more rigid (tighter) and collide faster. (fastest) Solid→Liquid→Gas (slowest)

Mechanical Waves

A vibration of particles in the medium (push or pull). This wave requires particles to collide to transfer energy.

Increases

As the frequency of a wave decreases, the period of the wave ___________.

Decreases

As the frequency of a wave increases, the period of the wave ___________.

As the wavelength of a wave in a uniform medium increases, its frequency will _____.

Decrease; the wavelength was increased and the frequency was decreased. Wavelength and frequency are inversely proportional to each other.

The affect of different slinky materials

Different materials also have differing degrees of springiness or elasticity. A more elastic medium will tend to offer less resistance to the force and allow a greater amplitude pulse to travel through it; being less rigid (and therefore more elastic), the same force causes a greater amplitude.

Frequency and Wavelengths

High frequency has a short wavelength. Low frequency has a long wavelength.

Amplitude

Identifies the amount of energy in a wave

Mechanical Wave Speeds

Lighter materials (less inertia) have faster wave speeds. Tighter (rigid or more tension) solids have faster wave speeds Hotter gases (more KE) have faster wave speeds **if wave speeds do not change, then if you increase the wavelength, you decrease the frequency (inverse relationship).**

Inertias affect on a Slinky

More massive slinkies have a greater inertia and thus tend to resist the force; this increased resistance by the greater mass tends to cause a reduction in the amplitude of the pulse.

Examples of Interference

Musical Beats - when waves of different frequency meet, they can be in-phase (loud sound) or out-of-phase (quiet sound). Creates wow-wow sound. Bubbles - when waves reflect off the front and back of the bubble and combine in-phase (bright color) or out-of-phase (color is missing). Creates a rainbow effect.

Frequency

Refers to the number of occurrences of a periodic event per time and is measured in cycles/second. EX. In this case, there is 1 cycle per 60 seconds. So the frequency is f = 1 cycle / (60 s) = (1 / 60) Hz **FREQUENCY IS THE RECIPROCAL OF THE PERIOD.** EX. The period is 5 seconds, so the frequency is 1/(5 s) = 0.20 Hz.

Period

Refers to the time for something to happen. Aka the interval of time between successive occurrences of the same state in an oscillatory or cyclic phenomenon, such as a mechanical vibration, an alternating current, a variable star, or an electromagnetic wave. measured in seconds/cycle. EX. In this case, there are 11 seconds per 33 vibrational cycles. Thus the period is (11 s) / (33 cycles) = 0.33 seconds. **PERIOD IS THE RECIPROCAL OF THE FREQUENCY**

As the wavelength of a wave in a uniform medium increases, its speed will _____.

Remain the same; the wavelength was altered but the speed remained the same. The same can be said about rows 3 and 4 and rows 5 and 6. The speed of a wave is not affected by the wavelength of the wave.

Dissipation

Spreads out. Example: Sound gets quieter or light gets dimmer the further you are from the source, decreasing the amplitude as the wave spreads out. The wavelength period and frequency do not change.

Energy Transported by a Wave related to Amplitude

The amount of energy carried by a wave is related to the amplitude of the wave. A high energy wave is characterized by a high amplitude; a low energy wave is characterized by a low amplitude. The energy transported by a wave is directly proportional to the square of the amplitude. So whatever change occurs in the amplitude, the square of that effect impacts the energy. This means that a doubling of the amplitude results in a quadrupling of the energy. Equations are guides to thinking about how a variation in one variable affects another variable.

Amplitude and Wave Speed

The amplitude of a wave does not affect the speed at which the wave travels. The speed of a wave is only altered by alterations in the properties of the medium through which it travels.

How amplitude related energy transported by a wave.

The energy transported by a wave is directly proportional to the square of the amplitude of the wave. This energy-amplitude relationship is sometimes expressed in the following manner. E=A^2 This means that a doubling of the amplitude of a wave is indicative of a quadrupling of the energy transported by the wave. A tripling of the amplitude of a wave is indicative of a nine-fold increase in the amount of energy transported by the wave. And a quadrupling of the amplitude of a wave is indicative of a 16-fold increase in the amount of energy transported by the wave.

Heat of a Gas

The heat of the gas will add more energy and increase wave speed. This is because heating the gas changes the medium, makes more kinetic energy, and the particles move faster.

The speed of a wave depends upon the ____.

The properties of the medium through which the wave is moving. An alteration in the properties of the medium will result in a change in the speed at which the wave moves through that medium.

What would effect the speed of a water wave? (The speed of a wave depends upon...)

The speed of a wave is dependent upon the properties of the medium through which the wave is moving. An alteration in the properties of the medium will result in a change in the speed at which the wave moves through that medium. (...the properties of the medium through which the wave travels)

Frequency and Wave Speed

The speed of a wave is unaffected by changes in the frequency. Doubling the frequency of a wave source does nothing to the speed of the waves.

The speed of a wave is defined as ______.

The wave speed refers to the distance traveled by a point on the wave pattern per unit of time. It is often measured in units such as meters/second and describes how fast the wave is moving through the medium. The speed of the wave depends on the medium in which it is traveling.

Wavelength and Wave Speed

The wavelength of a wave does not affect the speed at which the wave travels. The speed of a wave is only altered by alterations in the properties of the medium through which it travels.

When two waves going opposite ways hit eachother...

They combine they're strength to become one

Tension

Tighter (rigid or more tension) solids have faster wave speeds

Standing Wave

a large amplitude wave formed from the addition of multiple waves of the same frequency overlapping. This makes an object resonate. **When you have a node on each end of the string, this is formed (i.e.,every ½ wavelength).**

Resonance

a standing wave forces an object to vibrate with high intensity when the standing wave's frequency matches the natural frequency of the object. (beat box demo)

Medium

material (substance) a wave travels through

Anti-node

max amplitude, constructive interference Points with Maximum Displacement

Natural Frequency

most objects have this at which they vibrate easily based on shape and mass. Example: flute vibrates at a high frequency (short λ) because it's short.

Alterations in a property of a wave and wave speed

will not affect the speed of the wave. Two different waves travel with the same speed when present in the same medium.