Waves And The Electromagnetic Spectrum

Question 1

Transverse waves

Answer 1

The vibrations are perpendicular to the direction of wave travel examples are:
All EM waves
Seismic waves
Ripples

Question 2

Longitudinal waves

Answer 2

The vibrations are parallel to the direction of travel
The waves squash up and spread out making compressions and rarefactions
Examples are:
Sound
P waves

Question 3

V = x/t

Answer 3

Wave speed = distance/time

Question 4

V = f x λ

Answer 4

Wave speed = frequency x wavelength

Question 5

Oscilloscope

Answer 5

You can use two microphones and an oscilloscope to find the wavelength of a sound

Question 6

Wave behaviour at boundaries

Answer 6

When a wave meets a boundary three things can happen

1. Absorption by the second material - usually turned into thermal energy
2. Transmission through the second material (refraction)
3. The wave is reflected

Question 7

Refraction

Answer 7

Waves at different speeds in materials with different densities so when a wave hits a boundary it changes speed
If this happens at an angle the wave will change direction (refraction) this will always bend towards the normal
Because different colours of light have different wavelengths this can lead to the wavelengths splitting up if the 2 ended of a block of glass are not parallel the spectrum will not turn back into white light

Question 8

Sound

Answer 8

These are caused by vibrating objects these vibrations cause compressions and rarefactions in the air
Sound waves can refract as they enter materials
Sound waves can be reflected by hard surfaces as it is harder for them to travel through these (echos)
No sound in space because it is a vacuum

Question 9

Ear

Answer 9

When a sound wave meant your ear drum it causes it to vibrate
These vibrations are passed on to tiny bones called ossicles through the semicircular canals and into the cochlea
These get turned into electrical signals that go to your brain

Question 10

Ultrasound

Answer 10

Ultrasound is sound with frequencies higher than 20000Hz. This is outside human hearing range

Question 11

Ultrasound uses

Answer 11

Medical imaging - ultrasound imaging is used as the waves can pass through the body but When they meet a boundary they reflect so you see the reflections of the foetus
Industry- find a flaw in a material

Echo sounding

Question 12

Infrasound

Answer 12

Infrasound is sound with frequency’s lower than 20Hz

Under our hearing

Uses
Some animals use this to communicate
Detecting seismic activity as they release these

Question 13

Reflection

Answer 13

The law of reflection - angle of incidence = angle of reflection