Section 3 - Waves

Question 1

What is wavelength(λ)?

Answer 1

The distance from one peak to the next

Question 2

What is frequency(f)?

Answer 2

The number of complete waves per second

Question 3

What is amplitude?

Answer 3

The height of the wave, from the rest(middle of graph) to the crest

Question 4

What is the period(T)?

Answer 4

The time it takes for one complete wave to pass a point

Question 5

What is the formula for frequency?

Answer 5

f = 1/T

Question 6

What is the formula for the velocity of a wave?

Answer 6

v = f*λ

Question 7

Ratio of kHz to Hz

Answer 7

1 : 1000

Question 8

Ratio of MHz to Hz

Answer 8

1 : 1000000

Question 9

Examples of transverse waves

Answer 9

Light, EM waves, ripples on water

Question 10

Examples of longitudinal waves

Answer 10

Sound/ultrasound, shock waves

Question 11

Definition of a transverse wave

Answer 11

The vibrations are at 90° to the direction energy is transferred by the wave

Question 12

Definition of a longitudinal wave

Answer 12

The vibrations are along the same direction as the wave transfers energy

Question 13

What do(and don’t) waves transfer?

Answer 13

Energy and information, but without transferring matter

Question 14

How can the direction of travel of waves be changed?

Answer 14

Waves can be reflected, refracted and diffracted

Question 15

What is reflection?

Answer 15

The wave rebounds off the object

Question 16

What is refraction?

Answer 16

The wave goes through the object but changes direction

Question 17

What is diffraction?

Answer 17

The wave spreads out when the pass through a gap or past the edge of an object

Question 18

The 7 electromagnetic waves

Answer 18

• Radio waves
• Microwaves
• Infra-red
• Visible light
• Ultra-violet
• X-rays
• Gamma rays

Question 19

Which wave has the highest frequency and lowest wavelength?

Answer 19

Gamma rays

Question 20

Which wave has the lowest frequency and the highest wavelength?

Answer 20

Radio waves

Question 21

Colours of visible light

Answer 21

Red, Orange, Yellow, Gave, Blue, Indigo, Violet

Richard Of York Gave Battle In Vain

Question 22

Use of radio waves

Answer 22

Communication

Question 23

Use of microwaves

Answer 23

Satellite communication(shorter wavelength can pass easily through the atmosphere)

Question 24

Use of infrared radiation

Answer 24

Electrical radiators and night-vision equiptment

Question 25

Use of visible light

Answer 25

Communication through optical fibres/photography

Question 26

Use of ultraviolet

Answer 26

Fluorescent lamps

Question 27

Use of X-rays

Answer 27

Viewing internal structures of objects and materials

Question 28

Use of gamma rays

Answer 28

Sterilising medical equipment/food

Question 29

Danger of microwaves

Answer 29

Internal heating of body tissues

Question 30

Danger of infrared radiation

Answer 30

Skin burns

Question 31

Danger of visible light

Answer 31

Eye damage

Question 32

Danger of ultraviolet light

Answer 32

Damage of surface cells(cancer) Skin burns Blindness

Question 33

Danger of X-rays

Answer 33

Cancer caused by long term exposure

Question 34

Danger of gamma rays

Answer 34

Cell mutation/cancer

Question 35

Law of reflection

Answer 35

Angle of incidence = Angle of reflection

Question 36

Where are the angles of incidence and reflection defined?

Answer 36

Between the ray and the normal - NOT between the ray and the surface

Question 37

Definition of the normal

Answer 37

An imaginary line at right angles to the surface(goes in both directions - both into the mirror and out of it)

Question 38

Three points of a virtual image

Answer 38

- The image is the same size as the object - The image is as far behind the mirror as the object is in front - The image is formed from diverging rays - Look at p 36 for how to answer the question

Question 39

What happens if a wave hits a different medium face on?

Answer 39

The speed changes but the speed remains the same

Question 40

What happens if a wave hits a different medium at an angle?

Answer 40

The speed changes and the wave is refracted

Question 41

When light passes into a denser medium...

Answer 41

it bends towards the medium

Question 42

When light passes a less dense medium...

Answer 42

it bends away from the medium

Question 43

A wave bends towards the normal because...

Answer 43

it slows down

Question 44

A wave bends away from the normal because...

Answer 44

it speeds up

Question 45

A triangular prism disperses white light because...

Answer 45

it doesn't have parallel boundaries

Question 46

Formula for refractive index

Answer 46

n = c(speed of light in vacuum) / v(speed of light in material)

Question 47

Speed of light in a vacuum

Answer 47

c = 3 * 10⁸ m/s

Question 48

Snell's law

Answer 48

When an incident ray passes into material: | n = Sin(i) / Sin(r)

Question 49

How to find the refractive index of glass using a glass block

Answer 49

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Question 50

Critical angle

Answer 50

When the angle of incidence results in r = 90°

Question 51

Above the critical angle...

Answer 51

total internal reflection occurs - no light leaves the medium

Question 52

How to investigate the critical angle

Answer 52

Page 39

Question 53

Using Snell's law to find critical angles

Answer 53

Sin(C) = 1 / n

Question 54

Optical fibres

Answer 54

- Made of plastic or glass - Consist of a central core surrounded by cladding that has a lower refractive index - The core is so narrow that light passing through it hit the core-cladding boundary at angles higher than C - Therefore the light is always totally internally reflected

Question 55

Analogue signals

Answer 55

Can take any value within a certain rage

Question 56

Digital signals

Answer 56

Can only take two values(on/off)

Question 57

What happens to analogue and digital signals as they travel?

Answer 57

- They weaken, and therefore need to be amplified along their route - They pick up interference/noise from electrical disturbances and other signals

Question 58

Multiplexing

Answer 58

Transmitting multiple signals at the same time with just one cable/EM wave - easier with digital sounds

Question 59

Quantisation

Answer 59

Rounding multiple values to a smaller set: more data is lost with an analogue signal than a digital signal

Question 60

When sound waves enter a denser medium...

Answer 60

they speed up and refract

Question 61

How to measure sound waves

Answer 61

Connect a sound wave receiver(such as a microphone) to an oscilloscope

Question 62

Measuring the speed of sound using an oscilloscope

Answer 62

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