CHAPTERS 13 & 14 (REGULAR PHYSICS)

CHAPTERS 26, 27, 28 AND 29(CONCEPTUAL PHYSICS)

Sound and Light

Sound

All Sounds are produced by the vibrations of material objects

Sounds waves are longitudinal; the medium goes through compressions and rarefaction

Characteristics of Sound Waves

Audible sound waves range from 20Hz to 20,000 Hz

Less than 20Hz is InfrasonicMore than 20,000Hz is Ultrasonic

Characteristics of Sound Waves

Frequency determines pitch High frequency = High pitch (Fast moving, SHORT

waves) Low frequency = Low pitch (Slow moving, LONG

waves)

Speed of sound depends on the medium and temperature of the medium Sound travels faster in solids and liquids and the

slowest in gases

Speed of Sound

Speed of sound in air at 25 degrees C is 346m/s

Speed of sound in air at 0 degrees C is 331m/s

Sonic boom: Breaking the sound barrier

Characteristics of Sound

Sound travels in ALL directions, in 3D

The Doppler Effect

The Doppler Effect: a shift in frequency that results from the motion of the source of sound

SONAR and Echolocation

SONAR: SOund Navigation And Ranging

Echolocation or biosonar: When animals emits pulses of sound and listen to echoes for location or for food. Bats and Dolphins are common examples

Sound Intensity

Sound Intensity or Loudness is measured in Decibles, dB (deci-Bel)

Sound doubles every 10 dB

Resonance

Resonance: a vibration at the natural frequency

Characteristics of Light

Light is an electromagnetic waveElectromagnetic wave: transverse wave made

of electric and magnetic fields at right angles to each other.

Characteristics of Light

All electromagnetic waves vary depending on frequency and wavelength.

Electromagnetic spectrum is the range of all electromagnetic fields

ROYGBIV

Electromagnetic Spectrum

Table 14-1Visible light includes all colors of the rainbowThe violet end has short wavelengths and

high frequency (high energy)The red end has long wavelengths and low

frequency (low energy)

Electromagnetic Spectrum

Radio Waves (longest wavelengths)MicrowavesIR (infrared) wavesVisible lightUltraviolet (UV)light X RaysGamma Rays (shortest wavelengths)

Characteristics of Light

All electromagnetic waves move at the speed of light

Speed of light is approx 3.0x10^8 m/s

Equation is c=fλ Notice the similarity to v=fλ

Reflection of Light

Texture of a surface affects the reflectionDiffuse reflection is when light hits a rough

surface and light scatters in all directionsSpecular reflection when light hits a smooth

surface and is reflected evenly

Reflection of Light

Incoming and reflected angles are equal

Characteristics of Color

Additive Primary – red green blueSubtractive Primary – Cyan magenta yellow

Colors in Art

Black is a colorWhite is a colorThese two are opposites

Colors in Science

White is light (all colors combined)Black is the absence of light (darkness)

Polarization of Light

Light scatters in all (360°) directionsIt can be polarizedPolarization is the alignment of

electromagnetic waves to be parallel to each other