2. Waves
• A wave is a disturbance that carries energy
through matter or space.
• Medium – the environment that the wave
travels in (ex: water, air)
3. Waves Transfer Energy
• Waves will spread out in all directions carrying
energy.
• The energy is conserved in the system following
both the law of conservation of momentum and
energy.
4. Waves transfer Energy
• EX: Water waves do work on a boat
• EX: Sound waves do work on your
eardrum
• EX: Light waves do work on your eye
6. Wave Speed
• The speed of a wave will depend on the
medium it travels through
• The state of matter determines the speed
of the wave.
– EX: In gases the particles are spread out so
the wave travels slower in gases
– EX: In liquids, the particles are closer together
so the energy is transferred quicker between
particles of that medium
– EX: In solids, the particles are tightly packed
together so the wave travels very quickly
through solids
8. Doppler Effect –
Occurs when the wave source is moving.
http://www.physicslessons.com/phe/doppler
eff.htm
• Image Simulation
• Breaking the sound barrier
9. Light Waves
• Light waves occur in different frequencies and
wavelengths
• Light waves are represented on the
electromagnetic spectrum
• The Electromagnetic Spectrum consists of
visible light and other waves that cannot be
seen.
12. The Electromagnetic Spectrum
• Consists of light at all possible energies,
frequencies, and wavelengths.
• Visible light is only a small part of the
spectrum.
• The spectrum also contains X-rays,
Ultraviolet rays, Radio Waves, Gamma
waves.
13. The Nature of Light
• Light acts as a wave in that it:
– produces interference patterns like water waves
– Follows the laws of reflection, diffraction, and refraction
14. The Nature of Light
• Light also acts as a particle
– These particles are called PHOTONS
– A beam of light is considered to be a stream
of photons.
– Photons do not have mass…they are like
“bundles of energy”
15. Light Wave Speed
• All electromagnetic waves in empty space
travel at the same speed
• The speed of light is: 3.00 x 108 m/s or
186,000 miles/second
• Light will travel slower when it has to pass
through a medium such as air or water
17. Wave Interference
• The combination of two or more waves of
the same frequency that result in a single
wave
• Two types:
– Constructive Interference
– Destructive Interference
21. Wave Interference
• Interference of Light Waves produce
colorful displays
• Ex: Soap bubbles often show reds, blues,
and yellows on their surface because of
the interference of light.
24. Wave Interactions
• Waves may interact with each other when
traveling through a medium
• There are 3 possible outcomes:
– Reflection, Diffraction, and Refraction
25. 1. Diffraction
• A change in the direction of a wave when the
wave finds an obstacle or an edge
26. 2. Reflection
• The bouncing back of a wave when the wave hits a
surface or boundary
27. Reflection of light
• Every object reflects some light
• Rough surfaces reflect light in many
directions
• Smooth surfaces reflect light in one
direction
28. Law of Reflection
• When light hits a
smooth surface, the
angle of incidence
equals the angle of
reflection.
29. 3. Refraction
• The bending of waves
when they pass from
one medium to another
• Causes the wave to
bend
• Prism Example:
• http://www.physicslesso
ns.com/exp33.htm
30. Laws of Refraction
• When light travels in a medium with a higher
speed to a medium where it slows down, the ray
is bent toward the normal
31. Laws of Refraction
• When light travels from a medium where it is
slower to a medium where it can travel faster,
light bends away from the normal
33. Wave Absorption
• Energy from the
wave is absorbed
into the medium
• Often as heat
(measured as
thermal energy).
34. Thermal Energy
• Thermal conductors have a high rate of
energy transfer
• Thermal insulators have a slow rate of
thermal energy transfer
• Rate of thermal energy transfer is
dependent on temperature, color, texture
and exposed surface area of the object.
35. Thermal Equilibrium
• The amount of thermal energy absorbed is
equal to the amount of thermal energy
emitted.
• The temperature remains constant.
