What is a wave?
- Waves are a transfer of energy.
What is a transverse wave?
- Transverse waves: the vibrations are perpendicular to the direction of the wave (water, EM waves)
What is a longitudinal wave?
- Longitudinal waves: the vibrations are parallel to the direction of the wave (sound) e.g. | | | ||| ||| | | ||
What is the electromagnetic spectrum?
- HIGHEST WAVELENGTH, LOWEST FREQUENCY
- Uses: RADIO: tv and radio, MICROWAVES: satellite communications, cooking food, INFRARED: electrical heaters, cooking food, infrared cameras, VISIBLE LIGHT: fibre optic communications, ULTRAVIOLET: energy efficient lamps, sun tanning, X-RAYS and GAMMA: medical imaging and treatments.
- LOWEST WAVELENGTH, HIGHEST FREQUENCY
What do all electromagnetic waves have in common?
- Electromagnetic waves are always transverse, travel at the same velocity through a vacuum.
What is amplitude?
- Amplitude: the maximum displacement of a point on a wave away from its undisturbed position (high amplitude = high volume).
What is the frequency of a wave?
- Frequency: the number of waves passing a point each second (high frequency = high pitch).
What is the time period of a wave?
- Period: the time taken for one wave to pass a point.
Wave equations
- T = 1/f
- v = fλ
- T: time period (s), f: frequency (Hz), v: speed (m/s), λ: wavelength (m)
Radio waves
- radio waves can be produced by, or can themselves induce, oscillations in electrical circuits
What is refraction?
- waves can refract, reflect, be transmitted, and be absorbed.
- Refraction is when waves change direction as they enter a new medium (air/glass/water)
If the medium is more dense
- the wave will slow down and
- move towards the normal
If the medium is less dense
- the wave will speed up and
- move away from the normal