Notes over Waves Waves Section 1: What are waves? A.
Rhythmic disturbances that carry energy without carrying matter are called ______________________. B. Molecules ____________________________ wave energy without themselves moving, like a line of people passing a ball. Notice the line of people moving sandbags without moving themselves C. ___________________________ waves use matter to transfer energy. Must use a medium to travel Medium is any form of matter. 1. _______________________________ wave ‐ wave energy causes matter in the medium to move up and down or back and forth at right angles to the wave. 2. _______________________________ wave ‐ matter in the medium moves forward and backward in the same direction as the wave. D.
_____________________ waves ‐ compressional waves caused by colliding air molecules. E. ____________________________waves ‐ transfer energy without using matter; the Sun emits electromagnetic waves that travel through space to Earth. Your eyes only detect a small amount of the total spectrum. Section 2: Wave Properties A. ____________________________ ‐ The measure of how high the crests are or how deep the troughs are; or the distance between the particles in a compression and rarefaction B. _________________________________ ‐ distance from the top of one crest to the top of the next crest or from the bottom of one trough to the bottom of the next trough; or the distance from compression to compression or rarefaction to rarefaction C. _____________________________ ‐ number of wavelengths passing a given point per second. For sound this is pitch ‐ measured in Hertz 1. Longer wavelengths result in ________________________ frequencies. 2. ________________________________ frequencies result in shorter wavelengths. 3. ______________________________________________ result from wavelengths and frequencies of light and sound v=λf
or
velocity = wavelength x frequency * Amplitude is loudness or the amount of energy carried by the wave D. Wave _________________________ ‐ how fast a wave travels through a medium 1. Mechanical waves travel faster in a medium in which atoms are __________________________ together 2. Electromagnetic waves travel faster in a medium with _______________________ atoms in it. 3. If we add energy to a system used to generate waves continuously we get a series of waves called __________________________________ waves. Pulse Wave
Periodic Wave
Periodic means that a motion repeats once every time interval T. T is called the period of the wave. Periodic waves are related to ____________________________________________________ (the swing of a pendulum, the bounce of a spring, or the rotation of an object). Section 3: Wave Interactions A. ______________________________: When a wave strikes an object or surface and bounces off. B. ______________________________ ‐ when a wave bends and changes speed as it moves from one medium to another. This causes a shift in the image of the object. C. ______________________________ ‐ the bending of waves around a barrier D. _____________________________________ ‐ two or more waves combine to form a new wave. 1. ___________________________ interference ‐ the crest of one wave overlaps the crest of another wave, making a larger wave. The waves pass each other and continue on unchanged. The amplitude of the resulting wave is the ___________of the two crests. 2. _____________________________ interference ‐ the crest of one wave overlaps the trough of another wave, making a smaller wave. 3. If waves of equal amplitude meet crest to trough, they ________________________ each other out. 4. Interference can be used in ____________________________ protection. 5. The position and motion of the particles, being moved by the wave, indicate their phase. Particles that have the same displacement & move in the same direction are _________________________. Particles that move in opposite directions are out of phase. 6. Damping is what makes the vibrations in a wave eventually ___________. Standing Waves:
A standing wave is a condition in which a segment of a wave moves from crests to troughs between two points (______________) which remain stationary. They _______________________________! An antinode is a point of maximum displacement. Label the nodes and antinodes of the following standing waves:
One Half Wave
Two Half Waves
Three Half Waves
_______________________ is the bending of a wave that results when the velocity of the
wave changes because it passed into different media. Refraction is observed when a pencil is
placed in a glass of water.
The velocity of the light wave is
slower in water than in air. The
different media cause the light
wave to bend, and as a result, the
pencil appears to bend.
A wave passes into shallow water, speed is slower and wavelength is shorter. A wave that
passes into deep water, speed is greater and wavelength is longer.
Index of ________________________: refraction toward the normal due to the velocity slowing
down or refraction away from the normal due to the velocity speeding up.
Examples:
_________________________________: change in frequency of a wave due to the
motion/distance of the source or the receiver; wave close very loud, move away “seems” to
change in frequency and amplitude
Examples:
_________________________________ occurs when a wave strikes a barrier and then, bends
around the edge of the barrier. Water waves and sound waves are examples of waves bending
around barriers.