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Bellringer

Bellringer. s = 50 cm/s λ = 10 cm f = ?. Characteristics of Waves. Part II. Reflection. When an object or a wave hits a surface through which it cannot pass, it bounces back. Reflection is the bouncing back of a wave or object from a surface.

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Bellringer

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  1. Bellringer • s = 50 cm/s • λ = 10 cm • f = ?

  2. Characteristics of Waves • Part II

  3. Reflection • When an object or a wave hits a surface through which it cannot pass, it bounces back. • Reflection is the bouncing back of a wave or object from a surface. • For example, if you throw a ball at a wall, the ball bounces back. The ball is reflected by the wall.

  4. Reflection • Sound waves bounce off walls and other hard surfaces. Reflected sound waves are called echoes. • Light waves bounce off mirrors and other shiny surfaces. You see your face in a mirror because light from your face bounces from the mirror to your eyes.

  5. Reflection • Law of Reflection - The angle of incidence is always equal to the angle of reflection.

  6. Refraction • When a wave enters a new medium at an angle, one side of a wave changes speed before the other side, causing the wave to bend. • Refraction is the bending of a wave due to a change in speed. Refraction happens only when a wave enters a new medium at an angle.

  7. Refraction • Light travels slower through water than through air. So, when light enters water, it slows down. • If a light wave passes from air into water - at an angle - one side of the light wave enters the water before the other side. This causes the light to bend.

  8. Diffraction • When a wave moves around a barrier or through an opening in a barrier, it bends and spreads out. • Diffraction is the bending and spreading out of waves. Diffraction happens when waves go around a barrier or through a hole in a barrier.

  9. Interference • There are two types of interference: constructive and destructive • Interference is what happens between waves that bump into one another. When waves interfere, the waves combine to form a single wave.

  10. Interference • Constructive interference happens when the crests of one wave pass through the crests of another wave. The two waves combine to make a wave with a larger amplitude. • Destructive interference happens when the crests of one wave pass through the low points of another wave. The two waves combine to make a wave with a smaller amplitude.

  11. Types of Seismic Waves • Seismic waves include P waves, S waves, and surface waves. • Earthquakes cause waves that move through the ground. Earthquake waves are called seismic waves.

  12. Types of Seismic Waves • P (primary) waves are longitudinal waves. P waves move more quickly then other types of seismic waves. • S (secondary) waves are transverse waves. S waves cannot travel through liquids, including Earth’s liquid outer core. Because of this, if you are on the other side of the planet, you can primarily only feel P waves. • Surface waves are a combination of of longitudinal and transverse waves. Surface waves move more slowly then P waves or S waves. They also cause more damage than P waves or S waves.

  13. Show waveform animationshere

  14. Types of Seismic Waves • Tsunamis are huge surface waves in oceans. They are caused by underwater earthquakes.

  15. Detecting Seismic Waves • A seismograph records the ground movements caused by seismic waves are they move through Earth. • Seismographs are instruments that measure earthquake waves. • Seismographs can be used to find where an earthquake happened by measuring the time between a P wave and an S wave. Seismographs can also be used to find underground resources, such as oil and water.

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