Waves Flashcards
What is a transverse wave?
A wave that’s vibrations are perpendicular to the direction of the wave.
What is a longitudinal wave?
A wave that’s vibrations are parallel to the direction.
What is the frequency of a wave?
The number of waves passing a fixed point per second measured in Hertz (Hz).
What is the amplitude of a wave?
The max. displacement a particle can achieve from its undisturbed position measured in metres (m).
What is the wavelength of a wave?
The distance from one point on a wave to the equivalent point on the next wave measured in metres (m).
What is the period of a wave?
The time taken for one complete vibration measured in seconds (s).
What is a medium?
Material.
What is refraction?
The change in direction of a ray passing through a medium.
What is a refractive index?
The way in which materials affect refraction.
What is the frequency of an ultrasonic wave?
Anything greater than 20,000hZ (20kHz)- beyond the range of human hearing.
What is echo sounding?
The use of ultrasonic waves for detecting objects under deep water and measuring the depth of water.
What are the two types of seismic waves?
P-wave (primary wave)
S-wave (secondary wave)
What are the characteristics of P-waves?
Longitudinal, travel at the speed of sound, travel at different speeds through solids and liquids.
What are the characteristics of S-waves?
Transverse, half as fast as P-waves, cannot travel through liquids.
What is the order of the Electromagnetic Spectrum?
Radio, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays.
Which waves on the EM spectrum are ionising radiation?
X-rays and gamma rays.
Describe a convex lens.
Wider in the middle than at the edges.
Describe a concave lens.
Wider at the edges than in the middle.
What is the principal focus or focal point?
The point at which the parallel rays entering the convex lens are brought to a focus.
What is the focal length?
The distance from the lens to the focal point.
What is a real image?
An image that is on the opposite side of the lens to the object and can be projected onto a screen.
What is a virtual image?
An image that is on the same side of the lens as the object and can only be seen by looking through the lens.
What is magnification?
The ratio of image height to object height.
What is specular reflection?
Reflection by a smooth surface in a single direction.
What is a transparent object?
An object that transmits light coherently so objects can be seen on the other side.
What is a translucent object?
An object that transmits light, but the rays are scattered so objects cannot be seen clearly.
What is an opaque object?
An object that either reflects or absorbs all light incident on them, so no light passes through them and objects cannot be seen through them.
What is a perfect black body?
An object that absorbs all infrared radiation incident on it and doesn’t reflect or transmit any infrared radiation.
