Waves, Light, Sound and Color Waves Transfer energy through matter or space Waves May be longitudinal Or transverse Waves Waves travel through a medium such as: water air solids Wave Properties reflection refraction interference Wave Properties Diffraction: the bending of a wave around the edge of a barrier. Reflection, refraction, diffraction and interference Sound waves Longitudinal waves Need a medium to travel through Speed of sound is 340 m/s in air Water 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 particles are called photons Light: Particle or wave? BOTH!! Light does not need a medium to travel through. Doppler effect Change in frequency and pitch of a sound. Due to the motion of either the sound source or the observer. Listen! Doppler effect of sound Doppler effect in light As stars move away from earth, there is a shift in the light towards 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!