Waves (Chapter P14) Flashcards
What is the equation for wave speed
wave speed = frequency x wavelength
What is the equation for speed
speed = distance / time
What is the name given to a reflected sound wave
An echo
What is reflection
When a wave hits an object an is then reflected at the same angle
What is refraction
Refraction is the change in speed of a wave when it reaches the boundary between two different materials.
It happens because materials have different optical densities.
It causes the wave to change direction.
What is a transverse wave
In a transverse wave vibrations are at right angles (perpendicular) to the direction of energy transfer
(direction of the wave).
These vibrations cause peaks and troughs.
Name some examples of transverse waves
Waves on the surface of water (ripples) and all electromagnetic radiation such as visible light
What is a longitudinal wave
In a longitudinal wave vibrations are in the same direction (parallel) as the direction of energy transfer
These vibrations cause compressions and rarefactions.
What examples are there of longitudinal waves
sound waves
What is the definition of a frequency
The frequency of a wave is defined as the number of vibrations per second (or the number of waves
per second).
The unit is Hz (Hertz)
What is the definition of time period
Time period is defined as the time for one vibration (or the time for one wave to pass a point).
The unit is s (seconds).
What is the definition of amplitude
The amplitude is the maximum displacement of a vibration from its rest position.
What is the definition of wavelength
The definition of wavelength is the distance from a point on a wave to the same point on the next
wave (peak to peak for example).
The unit is m (metres).
What is the relationship between time period and frequency
Time period = 1 / frequency
What is wave speed
Wave speed is the speed at which energy is transferred through the medium.
What is a specular reflection
Specular reflection happens when light is shone on smooth surfaces.
Parallel rays of incident light are reflected in a predictable manner and remain parallel to each other upon reflection.
What is diffuse reflection
Diffuse reflection happens on rough surfaces.
Parallel rays of light do not remain parallel to each other on reflection and are scattered in different directions.
What is the law of reflection
The angle of incidence equals the angle of reflection
What is a virtual image
A virtual image is one from which the light rays appear to come but don’t actually come from the image e.g. mirror
What is a real image
A real image is one where the light rays do come from the image
What happens to parallel rays of light when they enter a convex lens
In a convex lens parallel rays from a distant source of light are made to converge at a point known as the focal point
A distance called the focal length from the centre of the lens.
What happens to parallel rays of light when they enter a concave lens
In a concave lens parallel rays of light are made to diverge away from the lens. The focal point is on the same side of the lens as the object.
What is the equation for magnification
magnification = image height / object height
What is a transparent object
They are objects which let light through fully
