P12: Waves Flashcards
What are examples of transverse wave?
Ripples on water, electromagnetic and waves of strings
What are examples of longitudinal waves?
Sound and p-waves
What is the amplitude?
The maximum displacement of a point on a wave away from its undisturbed position
What is the wavelength?
The distance from a point on one wave to the equivalent point on the adjacent wave
What is the frequency?
The number of waves passing a point each second
What is the wave speed? What is the formula?
The speed at which the wave transfers energy through the medium. Wave speed = frequency x wavelength
What is the range of normal human hearing?
20Hz to 20KHz
What DON’T waves transfer?
Matter
What is the formula for wave frequency?
Number of oscillations / time
What is true about a particle in a wave?
It will always return to its rest position
What is a transverse wave?
A wave which has oscillations perpendicular to the direction in which the waves transfer energy
What is a longitudinal wave?
A wave which has oscillations parallel to the direction in which the waves transfer energy
Describe evidence that a wave moves and not the substance (e.g. water)
When an object is dropped on water, the waves spread out and travel across the surface
Describe evidence that a sound wave moves and not the air
The sound waves travel through the air in a tuning fork, but the air doesn’t travel away from the vibrating object as it would cause a vacuum
What is the relationship between amplitude and the energy a wave carries?
The bigger the amplitude, the more energy the wave carries
Describe a method to measure the speed of sound in air
Two people should stand apart, and one of them should bang 2 cymbals together. The crashing sound will delay as sound travels slower than light. Use a stopwatch to time the interval between seeing and hearing. Repeat several times and calculate mean. Use speed = distance/time
What do the parallel lines on a ripple tank represent?
The peak of a wave
What changes and stays the same when waves travel from one medium to another?
Wavelength and speed changes but frequency stays the same
Why does frequency remain constant when waves travel from one medium to another?
Because the source is producing the same number of oscillations per second
What is the effect of sound waves on the ear drum?
Sound waves enter the ear and cause the ear drums to vibrate, sending signals to the brain about what is being heard.
What are 2 uses of ultrasound?
Foetus scanning and dog whistles
In what state of matter is the speed of sound highest and why?
Solids because they are more rigid and hard to compress
What seismic wave is longitudinal?
P-waves
What seismic wave cannot travel through liquids?
S-waves
