Waves & The Big Bang Flashcards
Define: Electromagnetic radiation
Transverse waves comprised of electric and magnetic fields at right angles to each other which can travel without a medium. All EM waves travel at the same speed in a vacuum.
Define: Wave
Oscillations which transfer energy
Define: Electromagnetic spectrum
The full range of electromagnetic radiation from wavelength 10-15m to 104m
Gamma (shortest wavelength), X-ray, Ultraviolet, Visible, Infra-red, Microwave, Radio
Define: Longitudinal wave
The oscillations are parallel to the direction of energy transfer
Define: Transverse wave
The oscillations are perpendicular to the direction of energy transfer
Define: Sound wave
An example of a longitudinal wave
Define: Reflection
The ‘bouncing off’ of a wave from a surface. The angle of incidence = the angle of reflection
Define: Refraction
Waves undergo a change of direction when they cross an interface or boundary. Waves do not refract if they travel along the normal.
Define: Frequency
The number of complete waves per second. Measured in Hertz (Hz).
Define: Wavelength
The distance from one crest to the next crest on a wave. Measured in metres (m).
Define: Amplitude
The distance from the crest of the wave to the middle. The maximum oscillation height.
Define: Normal
A line perpendicular to the reflection/refracting surface at the point of incidence
Define: Echo
A reflection of sound
Define: Doppler effect
A change in observed wavelength and frequency of a wave due to movement of the source or the observer
Define: Red-shift
A change in the observed wavelength of light from distant galaxies due to their movement away from the Earth. The further away the galaxy, the greater the red-shift, meaning they are moving away faster
