Waves Flashcards
(28 cards)
What is the amplitude of a wave?
The maximum displacement of a wave from it’s resting position
What is frequency?
The number of waves passing a point in 1 second
What is wave speed?
The speed at which energy is transferred through a medium
What happens to waves at a boundary?
Absorbed, emitted, reflected
What is the human hearing range?
20Hz - 20kHz
How do humans hear sound?
Sound waves cause the ear drum to vibrate which causes the sensation of sound. The conversion of sound waves to vibrations of solids works over a limited frequency range
How are ultrasound waves used and what are they?
Ultrasound has a higher frequency than normal sound so cannot be heard. Ultrasound waves are partially deflected when they meet a boundary between two different mediums. The time taken for a reflection to reach a detector can be used to find out how far the boundary is. Ultrasound is used in medicine and in industry. Longitudinal wave
What are P waves?
Longitudinal waves, travel faster than S waves. Can go through liquids and solids. Not as damaging as s waves
What is an S wave?
Transverse, slower, can only go through solids, very damaging
What is a longitudinal wave and give examples?
The oscillations are parallel to the direction of energy transfer. E.g. sound
You have compressions and rarefactions
What are transverse waves and give examples?
The oscillations are perpendicular to the direction of energy transfer. E.g. electromagnetic waves
What is time period?
Time it takes for one wave to travel
What does amplitude and frequency represent in sound?
Amplitude - volume
Frequency - pitch
What are the use of echo soundings?
Uses high frequency sound waves to detect things in deep water or the water depth
What have seismic waves provided evidence for?
The structure of the earth
Why do refractions happen?
Difference in velocity of the waves in different substances
What is a lense?
Forms an image by refracting light
What types of image can be formed by a concave lense?
Always virtual
What types of images can be formed by a convex lense?
Real or virtual
What is specular reflection?
Reflection from a smooth surface in a single direction
What is diffuse reflection?
Reflection from a rough surface that causes scattering
What is the focus of a lens called?
Principle focus
What happens to a light ray when it enters a different medium?
It gets closer to the normal and slows down
What happens to a light ray when it exits a medium?
It gets further away from the normal and speeds up
