Unit 3 - Lesson 2: Waves and the EM Spectrum

Question 1

What do all waves carry?

Answer 1

Energy

Question 2

What do waves transfer?

Answer 2

Energy

Question 3

How do waves move?

Answer 3

Waves vibrate or oscillate.

Question 4

What two types of waves are there?

Answer 4

Transverse and Longitudinal.

Question 5

Describe the movement of a transverse wave.

Answer 5

Vibrations are from side to side at right angles (90 degrees) to the direction of travel.

Question 6

Describe the movement of a longitudinal wave.

Answer 6

There is one wavelength. There are compressions and rarefactions. Vibrations are in the same direction as wave is travelling.

Question 7

Give examples of transverse waves.

Answer 7

Any wave from the electromagnetic spectrum (including visible light):
(In order)
- Radio Waves
- Microwaves
- IR
- Visible Spectrum (Rainbow on the electromagnetic spectrum)
- UV
- X-rays
- Gamma-rays

Question 8

Give an example of longitudinal waves.

Answer 8

Sound. As longitudinal waves travel forward, they vibrate in the same direction as the wave is travelling.

Question 9

What are the properties of transverse waves? Provide/draw a diagram.

Answer 9

DIAGRAM: https://i.pinimg.com/736x/06/e1/b3/06e1b301ce43df0b3cfaf6f2658ab628.jpg

Transverse waves have a peak or crest.
Transverse waves have a middle (rest).
Transverse waves have a trough.

Wavelength (λ) - In transverse waves, this is the distance from one peak to the next.

Question 10

What are the properties of longitudinal waves? Provide/draw a diagram.

Answer 10

DIAGRAM: https://i.pinimg.com/736x/b8/11/97/b81197f3cffaa7944922514d8502829f.jpg

Longitudinal waves have compression at the start and end.
Longitudinal waves have rarefaction in the middle.
Longitudinal waves have wavelength.
Longitudinal waves have amplitude in the centre.

Wavelength (λ) - In longitudinal waves, this is the distance from one compression to the next.

Question 11

What is frequency (f)? What can change the frequency of a wave?

Answer 11

Frequency is the number of waves (passing a set point) per second. It’s measured in hertz (Hz). The only thing that can change the frequency of a wave is its source.

Question 12

What is period (T)?

Answer 12

Period is the time taken in seconds for one complete wave to pass a point.

Question 13

What is amplitude?

Answer 13

Amplitude is the height of waves (from rest to crest).

Question 14

What is speed?

Answer 14

Speed is how fast the wave is moving.

Question 15

What is velocity (v)?

Answer 15

Velocity is how fast the wave is moving in a given direction.

Question 16

How can we convert Hz into kHz?

Answer 16

Divide Hz by 1000.

Question 17

How can we convert kHz into Hz?

Answer 17

Multiply kHz by 1000.

Question 18

How can we convert kHz into MHz?

Answer 18

Divide kHz by 1000.

Question 19

How can we convert MHz into kHz?

Answer 19

Multiply MHz by 1000.

Question 20

What is the equation for calculating wave speed? Give your answer in word units and algebraic symbols.

Answer 20

Word Units:
Speed (m/s) = Frequency (Hz) x Wavelength (m)

Algebraic Symbols:
V = f x λ

Question 21

What is the equation for calculating frequency or time period?

Answer 21

Frequency = 1/Time Period
OR
Period = 1/Frequency

Question 22

What is created when many waves travel in the same direction together?

Answer 22

A wavefront.

Question 23

What is a wavefront?

Answer 23

These are planes (like a flat sheet) joining all the points of the wave, that are vibrating, together.

Question 24

What is the distance between each wavefront equal to?

Answer 24

The distance between each wavefront is equal to one wavelength.

Question 25

How can we show wavefronts? What can we use?

Answer 25

We can show wavefronts using a ripple tank.

Question 26

How are uniform waves created?

Answer 26

Uniform waves are created in a tank of water by a paddle that is dipped into the water at regular intervals via a motor. A light shone down through the waves projects their shadow onto a screen below. A wavefront is a line where the water is affected by the wave in the same way at the same time. The wave crests are a part of the wavefront where the water is lifted to its maximum displacement (movement from its original position).

Question 27

Provide a picture/sketch of the way in which uniform waves are created.

Answer 27

https://i.pinimg.com/736x/eb/13/bf/eb13bfa924dfd0400197af8428223c4a.jpg

Question 28

When waves are forced through a large opening, what do we see?

Answer 28

When waves are forced through a large opening, we see plane (straight) wavefronts.

Question 29

What happens to the wave's shape as the gap/opening gets smaller?

Answer 29

The smaller the gap, the more curved the waves become.

Question 30

Does the distance between wavefronts change as they move through a gap/opening?

Answer 30

No. The distance between wavefronts does not change as they move through the gap.

Question 31

SPACER: END OF REVISION SHEET 1 - START OF REVISION SHEET 2

Answer 31

GO ONTO THE NEXT FLASH CARD TO START REVISION SHEET 2

Question 32

What is the Electromagnetic (EM) Spectrum?

Answer 32

The electromagnetic (EM) spectrum is a list of transverse waves organised in order of their wavelength and frequency.

Question 33

What do we call the waves on the electromagnetic spectrum?

Answer 33

Electromagnetic waves OR radiation.

Question 34

In what order is the electromagnetic spectrum? Give a mnemonic too.

Answer 34

Radio → Microwave → Infrared → Visible → Ultraviolet → X-ray → Gamma Ray Mnemonic: Raging Monkeys Invade Venus Using X-ray Guns.

Question 35

What are the frequencies (Hz) of the electromagnetic waves in the electromagnetic spectrum?

Answer 35

Radio: 10^4 Microwave: 10^8 Infrared: 10^12 Visible: 10^15 Ultraviolet: 10^16 X-Ray: 10^18 Gamma Ray: 10^20

Question 36

What is the wavelength (meters) of each electromagnetic wave in the electromagnetic spectrum?

Answer 36

Radio: 10^3 Microwave: 10^-2 Infrared: 10^-5 Visible: .5 x 10^6 Ultraviolet: 10^-8 X-ray: 10^-10 Gamma Ray: 10^-12

Question 37

Does wavelength decrease or increase from radio to gamma rays?

Answer 37

Wavelength decreases.

Question 38

Does frequency decrease or increase from radio to gamma rays?

Answer 38

Frequency increases.

Question 39

Can the amplitude of EM waves change?

Answer 39

Yes.

Question 40

Is wave speed the same or different for all transverse waves in free space (a vacuum)?

Answer 40

Wave speed is the same for all transverse waves in free space (a vacuum). This is the speed of light (because it's an example of EM radiation).

Question 41

What is the speed of light? Give your answer in m/s, km/s, and km/h.

Answer 41

3 x 10^8 m/s. In km/s, the speed of light is exactly 299,792.458 in vacuum. It's approximately 300,000 km/s. In km/h, the speed of light is 1,080,000,000.

Question 42

Give two examples of mediums in which speed can change.

Answer 42

Air and wave.

Question 43

Which EM radiation can be seen with the naked eye?

Answer 43

Visible light.

Question 44

What colours does visible light come in?

Answer 44

All the colours of the rainbow

Question 45

Does each colour have a different wavelength?

Answer 45

Yes

Question 46

What is an object's colour dictated by?

Answer 46

The wavelengths it absorbs and reflects.

Question 47

What does the eye absorb when perceiving colour?

Answer 47

The reflected colour.

Question 48

What is the order of colour in visible light? Give a mnemonic.

Answer 48

Red, Orange, Yellow, Green, Blue, Indigo, Violet Richard, Of, York, Gave, Battle, In, Vain

Question 49

Which colour in visible light has the longest wavelength and lowest frequency?

Answer 49

Red light has the longest wavelength and lowest frequency.

Question 50

Which colour in visible light has the shortest wavelength and highest frequency?

Answer 50

Violet light has the shortest wavelength and highest frequency.