Definition
amplitude The maximum distance of particles in a wave from their normal positions.
converge To come together
convex lens A lens which is thicker in the middle than at its edge
electromagnetic waves A group of waves that all travel at the same speed in a vacuum, and are
all transverse
eyepiece lens The lens on a telescope closest to the observer's eye
focal length The distance from a convex lens to the point where the image of a very distant
object is produced.
frequency The number of waves passing a point each second
geocentric Earth-centred
heliocentric Sun-centred
image Picture formed by a mirror or lens
lens shaped piece of glass or other transparent material that refracts light in particular ways
light energy The energy of visible light
light waves Electromagnetic waves that can be detected by the human eye
longitudinal E.g. sound waves, where the direction of energy transfer is parallel to the direction
of vibration which causes them
longitudinal waves Waves in which particles move back and forth in parallel with the direction
of movement of the energy
medium Something through which waves travel
Milky Way The name of our galaxy
naked eye Observation made using just the eyes, without using a telescope or any other aid
normal Line at right angles to the surface of a mirror or lens where a ray of light hits it
objective lens The lens in a telescope nearest the object to be observed
primary mirror The main mirror in a reflecting telescope which converges light to form an image
reflect When a wave bounces off a boundary between two materials
reflecting telescope A telescope in which the focussing of the main image is done by a curved
mirror
refracting telescope A telescope consisting of a series of lenses
refraction The change of speed and direction of a wave when it enters a new material
seismic waves Waves produced by an explosion or earthquake and which travel through the
Earth. They include P-waves and S-waves
sound energy The energy transferred by sound waves
sound wave Transverse seismic waves that travel through the earth
telescope A device for producing magnified images of distant objects
transfer To move something
transverse waves Waves in which movements are at right angles to the direction of movement
of the energy
visible light Electromagnetic waves that can be detected by the human eye
wave speed The distance that a wave travels in one second
wavelength The distance between a point on one wave and the same point on the next wave.
Date