P5- Waves

Question 1

Longitudinal

Answer 1

Vibration/energy transfer PARALLEL to oscillation/wave travel

Question 2

Transverse waves example + property

Answer 2

All electromagnetic waves, water ripples, S waves

- they cannot travel THROUGH liquid just on the surface

Question 3

Refraction to a lower density

Answer 3

Faster = increased wavelength

Also travels AWAY from the normal as the wave speeds up

Question 4

Refraction to a higher density

Answer 4

Slower = decreased wavelength

- also travels TOWARDS the normal

Question 5

White light

Answer 5

• all have slightly different wavelengths
  = in a denser substance they travel at diff speeds = short wavelengths are slower (violet) and therefore they refract more than red e.g.

Question 6

Why does violet refract more that red from glass to air

Answer 6

Violet speeds up more from glass to air SO it refracts more (as violet has a shorter wl)

Question 7

How to IR sensors detect people and why don’t they detect objects or people covered in foil

Answer 7

Humans emit more IR as they are hotter - so this is detected
Objects don’t emit IR, they are the same temp as surroundings so no change will be detected
Foil will reflect back IR to person, so not enough IR will be detected

Question 8

How to microwaves heat milk

Answer 8

Heat water molecules in milk - vibrate, kinetic converts to thermal

Question 9

Why are microwaves not affected by black or white beakers but IR is?

Answer 9

Microwaves are not absorbed by glass (don’t heat up) but black absorbs more IR and white reflects more IR

Question 10

EM waves from low to high frequencies

Answer 10

Radio, micro, IR, visible light, UV, X-RAY, gamma