waves 5.1 Flashcards
what is the definition of a wave
an oscillation that transfers energy
top of a wave
peak
bottom of a wave
trough
what is a wavelength
distance between two points on the same point on consecutive waves
frequency
number of oscillations per second (hertz)
Longitudinal wave examples
sound waves
p-waves
(need a medium (matter) to travel through)
transverse wave example
EM waves
s-waves
(don’t need a medium to travel through)
wave speed/ velocity formula
frequency (Hz) x wavelength (lambda/ meters)
How to measure velocity of ripples
use a ripple tank
use a light strobe and ruler and frequency to find number of rotations of the motor per second
how to measure velocity of sound
microphones and oscilloscopes
measure distance apart
time for sound to travel between them
calculate speed/ velocity
wave travelling from one medium to another can…
change velocity
change direction
(called a refraction)
when à wave travels from one medium to another the frequeny…
stays the same
what can happenwhen a wave hits à boundary between two media
reflected
transmitted (refracted)
absorbed
depends of density of the regions
what is an ultrasound
à frequency greater than 20000 Hz
often heard by dogs
How is an ultrasound used in pregnancy
Transmitter beams ultrasound waves into mother
waves reflect from different boundaries
machine calculates distance using time and velocity
distance produces an image
what happens when a sound wave hits a solid
sound gets reflected then absorbed
particles in a solid vibrate and gets hotter
what is a transducer
device that produces ultrasound waves by causing a crystal to vibrate rapidly
depth of boundary formula
depth of boundary =
speed of ultrasound waves x transit time x 1/2
what is wave phenomena
velocity changing
wavelength changing
frequency staying the same
between boundary of two media
why we can’t hear after a certain age
hairs inside cochlea have different lengths
which resonate with different frequencies
older you are= shorter her the hairs, harder to hear higher frequencies
how you hear using ears
outer ear and pinna gather sound waves
ear drum vibrates , causes ossicles to vibrate
amplifies vibrations and passes to inner ear through oval window
EARS CONVERT SOUND INTO ELECTRICAL SIGNALS
