Waves

Question 1

1. What do waves do?
2. What are the two types of wave?

Answer 1

1. Waves transfer energy from one place to another
2. The two types of wave are longitudinal and transverse

Question 2

How do the two types of waves vibrate?

Answer 2

Longitudinal waves vibrate parallel to the direction of wave travel (Horizontally)

Transverse waves vibrate at a right angle to the direction of wave travel (Vertically)

Question 3

1. What is time period?
2. What is frequency?
3. What is a wavelength

Answer 3

1. Time period is how long it takes a wave to travel a full wavelength
2. Frequency is how many waves travel past a point every second
3. Similar to frequency, it is the distance from peak to peak in a wave.

Question 4

What equation links time period a frequency?

Answer 4

T = 1 / f

1 = f X T

T = Time (seconds)
F = Frequency (Hertz)

Question 5

1. What is the relationship between amplitude and noise?
2. What is the relationship between wavelength and pitch?

Answer 5

1. The larger the amplitude, the louder the sound
2. The smaller the wavelength, the higher the pitch of the sound

Question 6

What is the wave speed equation?

Answer 6

V = f X λ

f = V / λ
λ = V / f

V = Velocity (m/s)
f = Frequency (Hz)
λ = Wavelength

Question 7

1. What is the speed of light?
2. What waves travel at the speed of light?

Answer 7

1. The speed of light is 300,000,000 m/s (3x10^8m/s)
2. All electromagnetic waves (EM waves) travel at the speed of lights

Question 8

1. What waves reflect if they hit a reflective surface?
2. How do humans see ourselves in the mirror?

Answer 8

1. All EM waves will reflect if the hit a reflective surface
2. Humans see themselves in the mirror when light reflects off the mirror

Question 9

What does the law of reflection state? What is it true for?

Answer 9

The law of reflection states that:

angle of incidence (°) = angle of reflection (°)
i (°) = r (°)

The law of reflection is true for any type of wave being reflected of any surface

Question 10

What happens when an EM wave travels into a material that has a higher refractive index?

Answer 10

The wave refracts towards the normal

This can also be shown with wave fronts

Question 11

What happens to an EM wave in a more dense material (like glass)?

Answer 11

The wave travels more slowly, the wavelength therefore decreases

Question 12

What does the big bang theory suggest?

Answer 12

The big bang theory suggests that the universe began from a small point that was (infinitely) hot and dense. It then exploded to form the universe

Question 13

What is the red-shift?

Answer 13

The red-shift is the main evidence for the big bang and it is the fact that wavelength of light from the most faraway galaxies is increases. It shows that the universe is expanding.

Question 14

1. What do all EM waves share?
2. Which 3 EM waves are the most ionising?

Answer 14

1. They are all transverse and travel at the speed of light
2. The 3 most ionising EM waves are: UV, X-rays and Gamma rays

Question 15

What is the order of visible light?

Answer 15

Red, Orange, Yellow, Green, Blue, Indigo, Violet (ROYGBIV)

Question 16

What are the 7 EM waves (in order)?

Answer 16

Gamma, X-rays, UV, Light (Visible light), Infra Red, Microwaves and Radio waves

Question 17

As you go from left to right (Gamma, X-rays, UV, Light, Infra Red, Microwaves, Radio waves), what happens?

Answer 17

a) The wavelength increases
b) The frequency decreases
c) The energy decreases
d) The danger decreases

Question 18

Name a use and danger of each EM wave.

Answer 18

Gamma:
Use: Sterilisation, Kills cancer cells
Danger: Can damage/mutate cells

X-rays:
Use: Imaging luggage, X-raying bones
Danger: Can damage/mutate cells

UV:
Use: Security Marking, Sunbeds
Danger: Sun burn, Can cause skin cancer

Light:
Use: Seeing, fibre optic communication
Danger: Blindness

Infra Red:
Use: Remote control, Heating, Night vision
Danger: Skin burns

Microwaves:
Use: Satellites, Phone, Cooking
Danger: Internal tissue heating

Radio waves:
Use: Radio, TV
Danger: None