Waves Flashcards
What are transverse waves?
Oscillations are perpendicular to the direction of energy transfer.
Examples of transverse waves?
All EM waves
Ripples and waves in water
What are longitudinal waves?
Oscillations are parallel to the direction of energy transfer.
Examples of longitudinal waves?
Sound waves
Shockwaves
What is the frequency?
The number of complete waves passing a certain point per second.
What is the equation linking freq and time period?
T = 1/f
What is the equation linking wave speed, freq and wavelength?
wave speed = frequency x wavelength
What is refraction?
Waves chaning direction at a boundary
Ripple tank practical?
FREQUENCY -Take slow motion video of waves -count waves passing point in 10 seconds -freq=no of waves/ 10 WAVELENGTH -Take camera image -count number of waves over 50 cm -wavelength= 30/no of waves WAVESPEED -speed=freq x wavelength
Air and glass?
-Air is less dense than glass so can pass more easily through it
Air TO glass?
-ray slows down so bends towards the normal
glass to air?
-ray speeds up so bends away from normal
Side entering the glass first?
-slows while the opposite side continues at faster speef
Upon entering the glass?
- speed and wavelength decrease
- frequency stays the same
What do white objects do?
reflect all wavelenghts
What do black objects do?
Absorb all wavelengths
What do transparent objects do?
Transmit light
What are colours?
specific wavelengths of light
What is a real image?
When the light rays meet at focal point
What is a virtual image?
When the light rays not actually at focal point
What is a black surface better at?
absorbing and emitting radiation than a white one
What is a matt surface better at?
absorbing and emitting radiation than a shiny one
What is the perfect black body?
An object that absorbs all of the radiation that hits it. No radiation is reflected or transmitted
What do black bodys absorb?
All electromagnetic radiation
What are black bodies good for?
emitting radiation
The hotter the temperature of bbr?
- The lower the peak
- The steeper the initial intensity increase
- The higher the intensity of the wavelengths
What are sound waves caused by?
vibrating particles
longitudinal wave
What does sound travel faster in?
solids
Why can’t sound travel in space?
- vacuum
- no vibrating particles
loudness=
amplitude
Freq=
pitch
Hearing?
- Sound waves cause ear drum to vibrate
- vibrations passed on to cochlea
- cochlea turns vibrations into electrical signals which get sent to brain
What is the hearing range?
20-20kHz
What is human hearing limited by?
- size
- shape
- material of ear drum
What are ultrasounds?
sound waves with frequencies higher than 20,000Hz
What are ultrasounds used for?
- prenatal scanning
- depth measurement
Depth measurement equation?
depth = speed x time
———————
2
Why do you divide by 2 for depth measurements?
ultrasounds travels there and back
P- waves?
- Longitudinal
- Travel through solids and liquids
- Faster
S- waves?
- Transverse
- Travel through solids only
- slower
The outer core is?
liquid
The mantle is?
solid
