Progressive waves

“Looking out into the immensity of the universe, we stand at the shores of the cosmic ocean. Yet our earthly seas are no less beautiful, and the crashing surf reminds us that most of what we know about our world comes from information carried by waves.”

Carl Sagan

Waves

• A basic concept of physics

• Progressive waves

• Describing waves

• Longitudinal

• Transverse

Graphical representation

• Displacement - time graph

• Transverse mechanical wave

• Longitudinal wave

• Amplitude

• Wavelength

• Frequency

Wavelength, frequency and wave speed

• A wave source vibrates at f vibrations per secondparticles of transmitting medium vibrate at same frequency

• 1 complete vibration = 1 wave generated disturbance = m from source = f or c = f

• Note: this is not on data sheet

Phase

• A and B: in phase

• B and C: in antiphase

• Phase difference • Calculating for x1 and x2

= 2 (x1- x2)

• If x1- x2 integer number s, = 2, 4, 6 etc

Path difference

• Waves emitted from a and B in phase

• At P: relative phase depends on distance travelled

• Path difference = BP – AP

• Path difference = n constructive

• Path difference = (n + ½ ) destructive