Waves, Light, Sound and Waves, Light, Sound and ColorColor

WavesWaves

Transfer energy through Transfer energy through matter or spacematter or space

WavesWaves

May be longitudinalMay be longitudinal

Or transverseOr transverse

WavesWaves

Waves travel through a medium Waves travel through a medium such as:such as:

water

air

solids

Wave PropertiesWave Properties

reflection

refraction

interference

Wave PropertiesWave Properties

Diffraction: the Diffraction: the bending of a bending of a wave around the wave around the edge of a barrier.edge of a barrier.

Reflection, refraction, diffraction Reflection, refraction, diffraction and interferenceand interference

Sound wavesSound waves

Longitudinal wavesLongitudinal waves

Need a medium to travel throughNeed a medium to travel through Speed of sound is 340 m/s in airSpeed of sound is 340 m/s in air

Water wavesWater waves

Water waves have transverse and longitudinal characteristics.Energy is transferred, but the particles stay essentially in the same place

Light: particle or wave?Light: particle or wave?

Light particles are called photonsLight particles are called photons

Light: Particle or wave?Light: Particle or wave?

BOTH!!BOTH!! Light does not need a medium to travel Light does not need a medium to travel

through.through.

Doppler effectDoppler effect

Change in Change in frequency frequency and and pitchpitch of a of a sound. sound.

Due to the Due to the motionmotion of either the sound of either the sound source or the observer.source or the observer.

Listen!Listen!

Doppler effect of soundDoppler effect of sound

Doppler effect in lightDoppler effect in light

As stars move away from earth, As stars move away from earth, there is a shift in the light towards there is a shift in the light towards the red end of the spectrum.the red end of the spectrum.

Color• When light strikes a surface, it can

be transmitted, absorbed, or reflected

Transmission of light• When light is transmitted, a

substance is said to be transparent.

• The color that is transmitted is the color that reaches your eye.

Transparent objects transmit color

• Red glass absorbs all colors of light except red, which it transmits.

Absorption of light

Reflection and absorption of light

• Opaque objects reflect and absorb light.

• The color of an opaque object is the color it reflects.

Opaque objects reflect and absorb light

• This apple reflects red and absorbs all other colors.

Translucent objects transmit some light

Color• Primary colors are red, green

and blue.• Primary colors may be

combined to make white light.

Complimentary colors• 2 colors that combine to form

white light.

Primary colors of light together form white light. But primary pigments together make black.

This is because they absorb all colors.

Bye-bye!