# WAVES A wave is a rhythmic disturbance that TRANSFERS ENERGY.

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WAVES A wave is a rhythmic disturbance that TRANSFERS ENERGY.

We are going to study 2 kinds of waves: Transverse Compressional
Both kinds of waves transfer energy. They just transfer the energy in different ways!

TRANSVERSE WAVE Transverse waves carry energy
by moving in an up and down motion. CRESTS- High points on a transverse wave TROUGHS- Low points on a transverse wave WAVELENGTH- Distance from crest to crest or trough to trough AMPLITUDE is the distance from resting position to the crest or trough.

Let's Draw One!

Frequency of a wave is the number of
crests to pass a point in 1 second. Look at the 2 waves below. Which one has a higher frequency? Yes, the second one has more crests, therefore a higher frequency!

1. 2. Is there any relationship between frequency and wavelength?
Lets look at 2 different waves. The first wave has a high frequency and a short wavelength. 1. The second wave has a low frequency and a long wavelength. 2. So, the higher the frequency, the shorter the wavelength!

fast a wave is traveling?
How do we figure out how fast a wave is traveling? Velocity = Wavelength x Frequency YOU MUST KNOW YOUR UNITS!! Velocity is measured in meters per second. (m/s) Wavelength is measured in meters. (m) Frequency is measured in hertz. (hz)

Let's Practice! Example : What is the velocity of a wave with a frequency of 15,000 hertz and a wavelength of 4 m? Step 1: Write the formula. Velocity = Frequency x Wavelength Step 2: Plug in the numbers from the problem. Velocity = 15,000 hz x 4 m Step 3: Calculate the answer and be sure to add a unit! 60,000 m/s

REFLECTION: Reflection is when a wave strikes
a barrier and is bounced back. Examples: Looking in a mirror or hearing an echo! The angle in =the angle out!

REFRACTION Refraction is the bending of light
waves as they travel from one medium to another. Example: A prism making a rainbow. Light waves bending as they enter water.

Parts of the Electromagnetic Spectrum
The sun releases all parts of the EM spectrum. They include: Radio waves Radar waves Microwaves Infrared Visible Light Ultraviolet X- Rays Gamma Rays

Electromagnetic Spectrum
All parts of the electromagnetic spectrum have 3 things in common: They are all TRANSVERSE WAVES. They all travel at the speed of light. (300,000 km/s) 3. They do not need a medium to travel. What is a medium? A solid, liquid, or a gas!

frequencies and wavelengths!
Electromagnetic Spectrum What is the only difference between parts of the electromagnetic spectrum? The only difference between the parts of the electromagnetic spectrum is that they all have different frequencies and wavelengths!

Visible Light is part of the EM Spectrum and can be broken down into its component colors. RED ORANGE YELLOW GREEN BLUE INDIGO VIOLET The only difference between the colors is that they all have different wavelengths and frequency.

Why does a red shirt appear red?
Because it reflects the wavelength that represents red and absorbs the rest. Why do black pants appear black? Because they absorb all the wavelengths! This is also why wearing black in the summer makes you feel warm. Why do white socks appear white? Because they reflect all the wavelengths. This is also why we wear white in the summer. To try and stay cool!

Transmitting Light The type of matter determined how
much light will be transmitted through. Opaque Objects: Transmit no light. We cannot see through them. 2. Transparent Objects: Transmit all light. We see easily through them. 3. Translucent Objects: Transmit some light. We can only see outlines.

Sound is a Compressional Wave
Remember: Light is an transverse wave! Sound is a Compressional Wave Compressional Waves carry energy by moving in a side to side motion. Compression – Areas of a compression wave that are close together. Rarefaction- Areas of a compression wave that are spread apart. Wavelength- The distance between compressions.

Let's Draw One

Sound is a vibration through a medium Sound is a compressional wave.
UNLIKE LIGHT, SOUND MUST HAVE A MEDIUM TO TRAVEL!!

Speed of Sound How fast sound travels depends on 2 things:
The Medium- Sound travels fastest through SOLIDS! 2. Temperature- Sound travels slightly faster in warm temperatures Speed of Sound in “regular” air is 344 m/s!

Speed = Distance Time Calculating Speed of Sound Remember your units!
Speed is in meters per second. Time is in seconds. Distance is in meters.

THE HIGHER THE FREQUENCY,
How are frequency and pitch related? Pitch is the highness or lowness of a sound. THE HIGHER THE FREQUENCY, THE HIGHER THE PITCH!

Differences Between Sound and Light Light travels much faster.
Light 300,000 km/s Sound 344 m/s 2. Sound needs a medium and light does not. 3. Sound is a compressional wave and light is a transverse wave.

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