# What are the two types of waves?se. 10 123456789 11121314151617181920 212223242526272829303132 1.Saltwater and freshwater. 2.Longitudinal and Transverse.

## Presentation on theme: "What are the two types of waves?se. 10 123456789 11121314151617181920 212223242526272829303132 1.Saltwater and freshwater. 2.Longitudinal and Transverse."— Presentation transcript:

What are the two types of waves?se. 10 123456789 11121314151617181920 212223242526272829303132 1.Saltwater and freshwater. 2.Longitudinal and Transverse 3.Latitude and longitude 4.Convergent and divergent.

What are the parts (A, B, and C) of the following wave called? response. 10 A B C 1.Top, bottom and width. 2.Crest, trough and wavelength. 3.Compression, rarefaction and wavelength. 4.Superior, inferior and resultant. 1234567891011121314151617181920 212223242526272829303132

E What are these parts (A, B, and C) of the wave? nter your response. 10 1.Top, bottom and width. 2.Crest, trough and wavelength. 3.Compression, rarefaction and wavelength. 4.Superior, inferior and resultant... AB C 1234567891011121314151617181920 212223242526272829303132

E The material a wave travels through is the______. your response. 1.Host. 2.Solute. 3.Solvent. 4.Medium. 10 123456789 11121314151617181920 212223242526272829303132

E When a wave bends because it has entered into a new medium it is called what? nter your response. 1.Reflection. 2.Refraction. 3.Rarefaction. 4.Reduction 10 123456789 11121314151617181920 212223242526272829303132

Waves PS 9.18 PS 9.19 PS 9.20

Key concepts Know the two types of waves, the parts of each and examples of each. Know the electromagnetic spectrum. Know what a medium is and how different mediums affect the properties of waves. Know what happens when waves superimpose each other.

Waves Waves transfer energy from one place to another. They do this by vibrating something up and down, or back and forth. In almost all waves, the direction of wave motion is at 90° to the oscillation. For others, the oscillations are in the same direction as the wave.

Types of Wave There are two types of wave motion: transverse and longitudinal. You need to learn these names, and what distinguishes them. This is a transverse wave.

Transverse is the one most people can draw. The oscillations are at 90° (perpendicular) to the wave motion: One way of remembering this is that is looks like an s on its side. Transverse has two s's in it, longitudinal has none.

Wavelength Perhaps the simplest definition in waves is the wavelength. It doesn't take a genius to realize that this is the length of the wave :-)

The biggest mistake most people make is with drawing this on a picture of a wave. Draw a complete wave length - from the same point on each wave ripple: crest trough

Amplitude We call the amount of movement from equilibrium displacement. Amplitude is just the maximum displacement of a wave:

Frequency Frequency means how frequent. In other words, how often something happens per second. For a wave, frequency means: how many waves per second.

Longitudinal Waves Here the oscillations are in the direction of wave motion. Examples of longitudinal waves are sound, ultrasound and earthquake P-waves. P-waves

Longitudinal Wavelength Just like transverse waves, we can measure a wavelength and amplitude for longitudinal waves. Compression Rarefactiontransverse Wavelength is the distance between parts of the wave that are doing the same thing.

Sound Waves are Longitudinal Waves Sound is produced when a compression is made. It requires a producer and a medium to travel through. The more elastic the object, the faster sound travels.

Sound acts like other waves Echoes are reflected sound waves Sonar uses echoes to judge distance to obstructions Human hearing is 20,000 Hz, below 10 Hz is infrasonic, and above 20,000 Hz is ultrasonic.

Sound Waves move through matter not through empty space. Resonance is the vibration of another object struck by a wave of the correct frequency. Since the forks are identical, the second one receives the correct frequency to begin vibrating.

Electromagnetic Spectrum The only special thing about light is that our eyes can detect it. However, it is just a tiny part of a collection of electromagnetic waves that make up the electromagnetic spectrum.light They are all transverse waves. Like all waves, they can be reflected, refracted and diffracted and they all are energy.transverse wavesreflected refracted

Electro Magnetic Spectrum All parts of the elecrtomagnetic spectrum move at a speed of 3x10 8 m/s (speed of light) radio micro IR visible UV X gamma You need to know the order of waves in the electro magnetic spectrum! Remember this saying, matching the waves in order of decreasing wavelength or increasing frequency:radiomicroIRvisibleUVXgammawavelengthfrequency

Real Radio low frequency Men Microwave Inevitably Infra Red Visit Visible Ugly Ultra VioletRadioMicrowaveInfra RedVisibleUltra Violet eX X rays Girlfriends Gamma high frequencyX raysGamma It is the high frequency waves that are the most dangerous. long wavelength

Radio Waves These have the longest wavelengths and are used in telecommunications (radio and TV broadcasts, as well as portable phones and walkie talkies). Some radio waves come from space. Astronomers look at these waves using giant radio telescopes. The advantage of radio astronomy is that you can do it during the day, at night, and even when it's cloudy!

Microwaves Go to even shorter wavelengths than radio waves, and we come to microwaves. Microwaves are very useful in communications. Microwave ovens also use microwaves, as they can be tuned to match the vibrations of water molecules: The waves just make the molecules vibrate with a larger amplitude, which heats the food up.

Infra Red Beyond the red end of the visible spectrum is infra red. This is detectable by our skin as heat radiation.heat radiation A filament lamp emits light and heat radiation. The sun also emits huge amounts of infra- red radiation. It is this that keeps the Earth warm. heat radiationEarth

Visible Light Each color of light we see has a different wavelength and frequency. The longest wavelength light we can see is red, Any longer than this, and we cannot see it. The shortest wavelength light we can see is violet. Any shorter than this, and we see nothing.

Ultra Violet Beyond violet is a dangerous type of radiation called ultra violet. You can remember it's dangerous by the expression "ultra violent"! UV is also emited from the Sun. It is to this that our bodies respond when out in the sunshine for too long.Sun

A brown pigment is produced in the skin to help protect our living cells from destruction - or even cancer. UV is partly absorbed by the ozone layer, but it is still important to apply sunscreen as an extra layer of protection.

X-Rays Many of us have been to hospital to have an X-ray photograph taken of a broken bone. X-rays are even more dangerous than UV, but are amazingly useful. How else would you see what was going on inside you easily?UV

Having a few X-rays taken every year is not harmful to your health, and physicists have developed more sensitive detectors recently so that weaker X-rays can be used. X-rays are absorbed by bone, but pass almost perfectly through flesh.

Gamma Waves These are the most dangerous and penetrating form of electro- magnetic waves. Gamma rays are emitted by some radioactive nuclei.radioactive nuclei Gamma waves have the shortest wavelengths, and highest frequency. They are also produced during supernova explosions!

Despite the apparent danger, they can be amazingly useful. Amongst others, they are widely used in hospitals. Some medical imaging equipment involves the use of gamma rays. Gamma waves can also be used to kill cancerous cells by direct exposure.

The substance that the wave travels through is called the medium. Sound waves need a medium but electromagnetic waves (radio, infrared, ultraviolet, etc.) do not need a medium to travel through. This is why light can travel through space (vacuum) and sound cannot.

Reflection All waves will reflect off different surfaces. This means that instead of just passing into another medium, the waves bounce back.

The incoming ray of light is called the incident ray. We measure the angle it makes not to the mirror, but to an imaginary line at 90° to its surface: the normal. The law of reflection states: angle of incidence = angle of reflection i = r

Refraction Refraction, like reflection, often involves waves changing direction. However this isn't always the case.reflection Refraction is more subtle than reflection, since it involves waves changing speed when they pass from one medium into another.

Refraction of light. When light (or other electromagnetic waves) pass into denser mediums the waves find it harder to move and they slow down.electromagnetic waves This results in a change of direction.

Refraction Actions When light passes into less dense mediums, it speed up. In this case the waves bend away from the Normal:

Waves bend around the edge of an obstacle in their path, a behavior that is called diffraction. Water waves passing through slits are bent around the corners of the slit as they pass through giving an example of diffraction. When two or more waves superimpose, they are said to have interference.

Waves Java Applet http://www.learningincontext.com /PiC-Web/chapt08.htm

While interfering, it is possible that the wave pulses reinforce one another, causing the amplitude of the combined waveform to be greater, producing what is called constructive interference. On the other hand, if two pulses tend to cancel each other, the amplitude of the combined waveform is smaller. This is called destructive interference.

Seismic Waves The outer layer of the Earth is called the crust. This is broken into many separate pieces, called plates. Under this lies the mantle, a hot, fluid layer which makes the plates move over a long time.fluid Sometimes they shift slightly, leading to gigantic vibrations that pass both throughout the earth, and over its surface as earthquake waves.

Earthquake Waves There are four kinds of waves produced by an earthquake. Two move over the surface, causing damage, and two pass through the Earth itself - called body waves.

S and P Waves P-waves Primary waves are longitudinal waves that push and pull the earth. They are the fastest body wave, averaging speeds of about 6 km/s.longitudinal waves S-waves Secondary waves are transverse waves, which make the earth shake from side to side. Slower than P waves, they average about 4 km/s so arrive second.transverse waves

What are the two types of waves?se. 10 123456789 11121314151617181920 212223242526272829303132 1.Saltwater and freshwater. 2.Longitudinal and Transverse 3.Latitude and longitude 4.Convergent and divergent.

What are the parts (A, B, and C) of the following wave called? response. 10 A B C 1.Top, bottom and width. 2.Crest, trough and wavelength. 3.Compression, rarefaction and wavelength. 4.Superior, inferior and resultant. 1234567891011121314151617181920 212223242526272829303132

E What are these parts (A, B, and C) of the wave? nter your response. 10 1.Top, bottom and width. 2.Crest, trough and wavelength. 3.Compression, rarefaction and wavelength. 4.Superior, inferior and resultant... AB C 1234567891011121314151617181920 212223242526272829303132

E The material a wave travels through is the______. your response. 1.Host. 2.Solute. 3.Solvent. 4.Medium. 10 123456789 11121314151617181920 212223242526272829303132

E When a wave bends because it has entered into a new medium it is called what? nter your response. 1.Reflection. 2.Refraction. 3.Rarefaction. 4.Reduction 10 123456789 11121314151617181920 212223242526272829303132

Download ppt "What are the two types of waves?se. 10 123456789 11121314151617181920 212223242526272829303132 1.Saltwater and freshwater. 2.Longitudinal and Transverse."

Similar presentations