5A and 5B: Waves

Wave – a wiggle in space andand timeFor example: light and sound*A wave exists over space and time**

Transverse WaveMidpoint (Equilibrium)

Parts of a Transfers Wave

Crest (high point)

Trough (low point)

Amplitude - distance from midpoint to crest or trough

Wavelength () – distance from one crest (trough) to the next

Frequency (f)how frequently a vibration occurs

(# of crests per second)vibrations per second

Heinrich HertzThe unit of frequency is

the Hertz.

1 vibration per second = 1 Hertz

Frequency/wavelength relationship

• If frequency and pitch go then wavelength goes

• If frequency and pitch go then wavelength goes

25.3 Wave MotionSound and light waves

move.As waves move, matter is NOT passed along them. Movement of energy, not

material

For example:When you create a

wave with a rope, it is the disturbance that

moves along the rope, not the rope itself.

25.6 Longitudinal Wave

The energy compresses and expands along a straight

path.

Place a slinky on the ground and try to push and pull it.

Sound waves are longitudinal or compression waves.

25.7 Interference

Interference pattern: patterns formed when waves overlap

2 types of interference:1.constructive (adding)–

reinforcing interference when waves align at the crests and troughs**individual effects are

increased**

Constructive Interference- the result would be a larger wave

2.Destructive (subtracting)– cancellation interferencewhen the crest of one wave aligns with the trough of another**their individual effects are reduced**

Destructive Interference- the result would be a flat line

Sound Waves • Sound travels MUCH slower

than lightEX: lightening and thunder

• The speed of sound at room temperature is

340 m/s340 m/s

Natural frequency – amount of vibration in a certain time (frequency) that an object naturally tends to vibrate

•Resonance – a phenomenon that occurs when an object reaches its natural frequency (from another source)

EX: marching over bridges, opera singer breaking a glass by singing

Light waves are transverse waves.

Polarization – the filtering out of all vibrations in a certain direction- only letting waves in a certain direction get through

Reflection – bouncing off(flat surface parallel to H2O)

Refraction – penetrating (goes through)(flat surface perpendicular to H2O)

• Reflection – bouncing offex: mirrors, echos

• Refraction – penetrating (goes through), changes the way things look as they travel through materials of different densities.

Ex: straw in water, heat waves along a highway