Keep the Slinky in its box until further instructed. Waves Keep the Slinky in its box until further instructed. Clear off your tables! (binders/folders/Slinky boxes) Paper/pencil only!

Slinky Lab Ground Rules: You will have about 30-60 seconds to do the assigned task. Be GENTLE. Don’t shake too violently. The Slinky should NOT fall off of your table. LIGHTS OFF = HANDS OFF. Do not touch the Slinky again until instructed to. (Lights on)

What is a wave? Wave = A disturbance/vibration that transmits energy through matter or space A medium is a substance or material which carries the wave

Transverse Vibrates perpendicular (90) to the direction of wave travel Example: Electromagnetic waves Animation courtesy of Dr. Dan Russell, Kettering University

Transverse Use your Slinky to demonstrate a transverse wave: Work with a partner One of you move your end of the Slinky back and forth (left and right, like a snake crawling), perpendicular to its stretched length. The other student must hold his or her end of the Slinky still

Draw and label what your Slinky looked like when it created a transverse wave.

Longitudinal Vibrates parallel (in the same direction) to the direction of wave travel Example: sound waves Animation courtesy of Dr. Dan Russell, Kettering University

Animation courtesy of Dr. Dan Russell, Kettering University

Longitudinal Are composed of: Compressions, where the parts of the medium (coils of the Slinky) are CLOSER TOGETHER than normal Rarefactions, where the parts of the medium are FARTHER APART than normal

Longitudinal Use your Slinky to demonstrate a longitudinal wave: Work with a partner Stretch it out along the table One of you grasp and draw several coils of a stretched Slinky toward yourself Release the coils The other student must hold his or her end of the Slinky still

Draw and label what your Slinky looked like when it created a longitudinal wave.

Surface Waves A combination of longitudinal & transverse Example: Ocean waves Animation courtesy of Dr. Dan Russell, Kettering University

Electromagnetic Waves Wave which can transmit its energy through a vacuum or empty space. Example – light Produced by the vibration of electrons within atoms on the Sun's surface Travel through space until they reach Earth

Mechanical Waves Not capable of transmitting its energy through a vacuum (space) Require a medium in order to transport their energy from one location to another Example – sound waves, seismic waves

Keep the Slinky in its box until further instructed. Clear off your tables! (binders/folders/Slinky boxes) Paper/pencil only!

Slinky Lab Ground Rules: You will have about 30-60 seconds to do the assigned task. Be GENTLE. Don’t shake too violently. The Slinky should NOT fall off of your table. LIGHTS OFF = HANDS OFF. Do not touch the Slinky again until instructed to. (Lights on)

There are four things we can measure for waves: Wavelength Frequency Amplitude Speed

Wavelength Distance What is length a measure of? So what do you think a wavelength is? The distance across 1 FULL wave Distance WAVELENGTH WAVELENGTH

Which has a shorter wavelength?

Measuring Wavelength Does this tell us the distance between the two waves? Why not? You have to measure the distance between the same two points! (crest to crest, trough to trough, etc.)

Wavelength – Transverse Waves Waves with _________________ wavelength have more energy. Stretch the slinky out across the table. Make TRANSVERSE waves. Try to create waves with a LONG wavelength. Try to create waves with a SHORT wavelength. a shorter Which wave did you have to put more effort into creating?

Amplitude The distance between the crest or trough and the wave’s resting position (wave height). Crest Amplitude Resting Position Amplitude Trough

Which has a larger amplitude?

What does amplitude tell us about a wave? Which of these waves would cause more damage if it hit the shore? Which has the larger amplitude? Which wave has more energy? THAT’S AMPLITUDE!

Amplitude – Transverse Waves Waves with _________________ amplitude have more energy. Stretch the slinky out across the table. Make TRANSVERSE waves. Try to create waves with a LARGE amplitude. Try to create waves with a SMALL amplitude. a larger Which wave did you have to put more energy into to create?

We’ve been looking at transverse waves…What about longitudinal?

We’ll start with wavelength… There aren’t any crests or troughs in a longitudinal wave! WAVELENGTH WAVELENGTH

We look at the compressions and rarefactions instead. Wavelength is the distance from: Compression to compression Rarefaction to rarefaction

Wavelength – Longitudinal Waves Waves with _________________ wavelength have more energy. Stretch the slinky out across the table. Make LONGITUDINAL waves. Try to create waves with a LONG wavelength. Try to create waves with a SHORT wavelength. a shorter Which wave did you have to put more effort into creating?

On to amplitude… Longitudinal waves don’t have a resting point… so what do we do?

Amplitude We look at how compressed or how rarefied the spring or particles are. More compressed = larger amplitude Less compressed = smaller amplitude

Amplitude – Longitudinal Waves Waves with _________________ amplitude have more energy. Stretch the slinky out across the table. Make LONGITUDINAL waves. Try to create waves with a LARGE amplitude. Try to create waves with a SMALL amplitude. a larger Which wave did you have to put more energy into to create?

Frequency What does it mean that a friend comes over to your house “frequently”? Can you take a guess as to what the “frequency” of a wave is? The frequency of a wave tells us the number of waves that pass a given point in a certain amount of time.

What is the unit for frequency? Frequency is measured in Hertz (Hz) – waves/sec. If one full wave passes a point every second, it has a frequency of 1 Hz. (1 wave/1 sec = 1 wave/sec) What is the frequency for 3 waves in 1 second? What is the frequency for 6 waves in 3 seconds?

Which has a higher frequency?

How can you find the frequency of this wave? Step 1: pick a point on the wave. Step 2: count the waves that pass that point in ___ seconds.

Frequency – Transverse Waves Stretch the slinky out across the table. Have one person pick a point on the table and count how many waves pass that point Have another person count to 10 seconds. Make TRANSVERSE waves. Try to create a HIGH FREQUENCY wave. Try to create a LOW FREQUENCY wave. Try to keep the amplitudes the same in both waves.

Frequency – Transverse Waves Waves with _________________ frequency have more energy. Stretch the slinky out across the table. Have one person pick a point on the table and count how many waves pass that point Have another person count to 10 seconds. Make TRANSVERSE waves. Try to create a HIGH FREQUENCY wave. Try to create a LOW FREQUENCY wave. Try to keep the amplitudes the same in both waves. a higher Which wave did you have to put more energy into to create?

Wave Speed Option 1: Time how long a wave takes to get from point A to point B. A B

Wave speed = wavelength x frequency Option 2: Wave speed = wavelength x frequency Wave Speed = 8 meters/second Wavelength – 2 meters Frequency – 4 Hz. (4 waves pass every second)

Wave speed is affected by several factors The type of wave Example: Light vs sound (why you see lightning before you hear thunder) The medium the wave is moving through Example 1: You drop a penny into a pan of water & a pan of syrup – which hits first? Example 2: yelling underwater as opposed to above water (in air).