SIMPLE HARMONIC MOTION BALL IN A BOWL PENDULUM WATER WAVES SPRINGS GUITAR STRINGS SOUND LIGHT

WAVES ONE DIMENSIONAL WAVES CAN BE: PULSE CONTINUOUS STANDING

WAVES LONGITUDINAL WAVES SLINKY SOUND P-SEISMIC WAVES TRANSVERSE WAVES STRING WATER LIGHT S-SEISMIC WAVES OFTEN SINUSOIDAL (SINE WAVES)

MEASURES OF WAVES AMPLITUDE: ENERGY IN THE WAVE PERIOD: TIME BETWEEN PEAKS FREQUENCY: CYCLES PER SECOND SPEED = WAVELENGTH X FREQUENCY WAVELENGTH: DISTANCE BETWEEN PEAKS

SPEED OF SOUND HOW WOULD YOU DESIGN AN EXPERIMENT TO MEASURE THE SPEED OF SOUND? WHAT FACTORS WOULD CONTRIBUTE TO EXPERIMENTAL ERROR?

HOW CLOSE WAS THAT LIGHTNING BOLT? SOUND TRAVELS 700 mph in air at sea level 700 mph = 0.2 mps Or: 5 second to travel one mile How close was the lightning strike? Start counting off seconds after the bolt until you hear the thunder (1 mile for every 5 sec).

INTERFERENCE WAVES WILL PASS THROUGH EACH OTHER WITHOUT PERMANENT EFFECT THE MEDIUM MUST REACT TO THE SUM OF THE TWO (OR MORE) WAVES IF THE PEAKS CORRESPOND: AMPLIFICATION IF PEAK AND NODE CORRESPOND: REDUCTION IF PEAK AND ANTI-PEAK CORRESPOND: A NODE WHAT WOULD HAPPEN IF THERE WERE WAVE- MAKERS AT OPPOSITE ENDS OF THE WAVEPOOL?

SOUND IN A STRING SPEED OF WAVE DEPENDS ON: DENSITY OF STRING CROSS-SECTION OF STRING TENSION IN STRING

STANDING WAVES SKIPPING ROPE GUITAR STRING TUNING A GUITAR STRING CAN YOU HEAR THE BEAT?

STANDING WAVES First harmonic Second harmonic Third harmonic node loop

WIND INSTRUMENTS L = 3 0 /4 Flute, oboe, beer-bottle, organ...

DOPPLER SHIFT WHEN A WAVE TRAVELS THROUGH A MEDIUM ITS SPEED IS AFFECTED BY THE NATURE OF THAT MEDIUM. FOR EXAMPLE SOUND TRAVELS FASTER IN WATER OR STEEL THAN IN AIR. IF THE SOURCE OF THE SOUND VIBRATION IS ALSO TRAVELLING THIS WILL AFFECT THE PITCH, OR FREQUENCY OF THE WAVE, SINCE THE PEAKS WILL BE CLOSER OR FURTHER APART.

DOPPLER SHIFT SOURCE LISTENER SOURCE APPROACHING SOURCE RECEDING

ENERGY IN WAVES PARTICLES IN THE MEDIUM (STRING) MOVE AS THE WAVE PASSES PE = 1 / 2 k x 2 x is displacement KE = 1 / 2 m v 2 v = velocity or frequency POWER IN WAVE = AMPLITUDE 2 POWER IN WAVE = FREQUENCY 2

BREAKING THE SOUND BARRIER AS THE PLANE APPROACHES THE SPEED OF SOUND, WHAT HAPPENS THE SOUND ENERGY EMITTED BY THE PLANE IN A FORWARD DIRECTION? CHANGE IN AMPLITUDE? CHANGE IN FREQUENCY? INCREASED ENERGY?

HEARING DECIBELS VOLUME OF SOUND = 10 log (I/I o ) Whisper ~50 db conversation ~ 70 db pain threshold ~ 120 db Like the Richter scale for earthquakes 2 bel is 10 times one bel, 3 bel is 100 times one bel one decibel is one bel/10

ELECTROMAGNETIC RADIATION WHAT IS THE MEDIUM FOR LIGHT? THE EM SPECTRUM IS MUCH WIDER THAN THE VISIBLE SPECTRUM...GAMMA-X-UV-VISIBLE-IR-MICROWAVE-RADIO... violet - blue - green - yellow - orange - red

SNELL’S LAW a a mirror a

OPTICS SNELLS LAW MIRRORS PRISMS AND LENSES REFRACTION REFLECTION n=1 n=1.33 air glass Light always finds the “least time” path

TWO DIMENSIONAL WAVES WAVEFRONTS DIFFRACTION AND INTERFERENCE TWO-SLIT EXPERIMENT

INTERFERENCE FRINGES COLOURS IN AN OIL-SLICK ACTS LIKE A PRISM, IN REFLECTION WAVES CONSTRUCTIVELY OR DESTRUCTIVELY INTERFERE WITH EACH OTHER

INTERFERENCE

DIFFRACTION GRATINGS CAN ALSO GET INTERFERENCE FROM A REGULAR SPACED ARRAY OF LINES OR AN ARRAY OF ATOMS IN A CRYSTAL

ONE-SLIT???? N+1-wavelengths reinforcing cancelling N wavelengths reinforcing cancelling N+1/2 wavelengths

TWO-SLIT EXPERIMENT

CURVED MIRRORS F

LENSES

LENSES (2)

INTERNAL REFLECTION A A’ C’ B’ B C Brewster’s angle

FIBRE OPTICS CORE CLADDING n n’ > n