Waves (Behavior)

• Refraction means a wave bends as it moves from one substance into another. The bending of water waves around a barrier they encounter.
• Waves speed up or slow down depending on the substance and different ways is REFRACTION
• Reflection means a wave strikes an object or surface and bounces off. Formation of echo.
• Waves are partially transmitted and reflected when they strike the boundary of the medium, REFLECTION
• LAW OF REFLECTION STATES: The angle of incidence is always in the same to the angle of reflection
• If the angle of incidence is 30°, then the angle of reflection will also be 30°
• Angles are always measured from the normal (perpendicular to the mirror through the point of incidence), not from the mirror
• STATIC SOURCE: NOT MOVING; SAME FREQUENCY ALL THROUGHOUT
• Longer wavelength= low pitch = low frequency
• short wavelength= high pitch = high frequency
• Diffraction is the spreading or bending out of waves around an obstacle or round objects. Change in speed as a wave enters a different medium
• Size of the obstacle is of the same order of magnitude as the wavelength of the incidence wave.
• The incident wave approaches the boundary but hasn't yet, while the reflected wave moves away from it in the same medium as the incident wave.
• Wide gap = smaller diffraction effect
• Narrow gap = large diffraction effect
• Light bends as it passes around an edge of the object or through an opening, thus LIGHT CAN DIFFRACT.
• Interference is the meeting of two waves while traveling along the same medium.
• Constructive interference occurs when two waves travel in the same direction and phase, having greater amplitude.
• Example of constructive interference: two speakers next to each other, distance from one speaker to the observer is same. The path difference must be zero.
• Destructive interference occurs when two waves interact with equal amplitude. The interference of the waves results in zero amplitude. NO WAVE IS FORMED as they both will cancel each other.
• Light can undergo interference as the waves overlap and interfere, constructively (bright lines) and destructively (dark regions)
• Constructive interference has greater amplitude than the individual waves 
• Destructive interference has lesser amplitude than the individual waves 
• When waves are in phase, adding the amplitudes gives us the resultant wave. This is 

  CONSTRUCTIVE INTERFERENCE
• An example of destructive interference is noise-cancelling earphones. Background noise is detected, sound waves that are out of phase with the noise are produced, and DESTRUCTIVE INTERFERENCE results in zero, or reduced sound waves reaching your ears. 

  
• Distortions of underwater objects are an example of REFRACTION.
• Seeing a mountain range through a calm and clear lake is an example of REFLECTION.
• The Doppler effect is illustrated when an observer detects an apparent change in the frequency of sound waves produced by an airplane passing overhead.
• The Doppler Effect is the increased or decreased perceived frequency of any sound or light wave by a moving source. Applies to all types of waves. short wavelength= high pitch = high frequency / Longer wavelength= low pitch = low frequency