Waves, Sound, and EM Waves

Sound

• Example of compressional wave• Can travel through any type of

matter• Speed of sound depends on the

substance the medium is made of and whether it is solid, liquid, or gas

• In solids, particles are closer together so particles can transmit energy more quickly

• Travel fastest in solids and slowest in gas

Sound

• Speed of sound in air = 347 m/s• As the temperature of a substance

increases, its molecules move faster so sound waves move faster

Reflection

• Reflection = Bouncing back of waves

• Angle of Incidence equals Angle of Reflection

Refraction – bending of waves

Diffraction – spreading of a wave

Electromagnetic Spectrum

• Made of vibrating electric charges and can travel through space where matter is not present

• Energy transferred by vibrating electric and magnetic fields

• Speed of light 300000000 m/s • Fastest in gases and slowest in solids

Radio Waves

• Radio Waves– AM radio waves, FM radio waves,

Television• Microwaves

– Used in communication and heating foods

• Infrared Waves– Thermal energy– Hotter objects give off more IR waves

than colder objects

Visible Light

• Detected with eye• Colors

– ROY G BIV– Red-Orange-Yellow Green Blue-Indigo-

Violet• Shortest wavelength – Blue• Longest wavelength – Red

Gamma Rays

• Ultraviolet Waves– Useful in killing bacteria in objects

• X-rays– Can take images of organs, tissue, and

teeth• Gamma Rays

– Used in radiation therapy