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Physics Exam > P6 > Flashcards

P6 Flashcards

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1
Q

What is a Wave?

A

A wave is a disturbance or vibration that transfers energy from one place to another without transferring matter.

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2
Q

Example of waves

A

• Light (doesn’t move air particles)
• Sound (vibrates particles but they return to place)

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3
Q

Transverse Waves

A

The oscillations (vibrations) are perpendicular (at right angles) to the direction of the wave’s energy transfer.

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4
Q

Key features of a transverse wave: list

A

Crest
Trough
Oscillations
Energy travel

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5
Q
A
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6
Q

Key features of a transverse wave:

A

• Crest – the top of the wave.
• Trough – the bottom of the wave.
• Oscillations go up and down.
• Energy travels horizontally.

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7
Q

Examples of transverse waves:

A

• Light and all electromagnetic waves (radio, microwaves, etc.)
• Ripples on water
• Seismic S-waves (secondary earthquake waves)

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8
Q

Longitudinal Waves

A

The oscillations are parallel to the direction of the wave’s energy transfer.

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9
Q

Key features of a longitudinal wave: list

A

Compressions
Rarefactions
Oscillations

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10
Q

Key features of a longitudinal wave:

A

• Compressions – particles are squashed together.
• Rarefactions – particles are spread out.
• Oscillations move back and forth.

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11
Q

Examples of longitudinal waves:

A

• Sound waves in air
• Seismic P-waves (primary earthquake waves)

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12
Q

Differences Between Transverse and Longitudinal

A

direction of vibration
transverse vibrations are at 90 right angle to gthe directions the wave moves

longitudnal vibrations parrael to the direction the wave moves

motion transeverse wobble up and down

longitudinal squash and streches

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13
Q

Important Keywords

A
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14
Q

Important Keywords

A
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15
Q

What is a wave?

A

A disturbance that transfers energy without transferring matter.

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16
Q

In a transverse wave, which direction do oscillations move

A

Perpendicular to the direction of energy transfer.

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17
Q

In a longitudinal wave, which direction do oscillations move?

A

Parallel to the direction of energy transfer.

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18
Q

What is a crest?

A

The highest point on a transverse wave.

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19
Q

What is a compression?

A

Where particles are squashed together in a longitudinal wave.

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20
Q

What Is a Wave?

A

A wave transfers energy (not matter) through oscillations or vibrations.

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21
Q

FREQUENCY (f)

A

Frequency is the number of waves passing a point per second.

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22
Q

Example frequency

A

If 10 waves pass a point in 1 second, the frequency = 10 Hz.

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23
Q

PERIOD (T)

A

The time taken for one full wave to pass a point.

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24
Q

Don’t mix them up!
Period and frequency

A
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25
WAVE SPEED (v)
How fast a wave travels through a medium.
26
Don’t mix them up! Period and frequency
27
Don’t mix them up! Period and frequency
28
• λ (lambda) =
wavelength (m)
29
Wave Speed
How quickly energy is transferred by the wave
30
What is the unit of frequency?
Hertz (Hz
31
Measuring the Speed of Sound Using an Oscilloscope What Are You Measuring?
The speed of sound in air, using two microphones connected to an oscilloscope.
32
Step-by-Step Method
1. Connect both microphones to an oscilloscope. 2. Place the microphones a measured distance apart (e.g., 1 metre). 3. Make a sharp sound (like clapping) near the first microphone. 4. The sound will be detected at slightly different times by each microphone. 5. On the oscilloscope, you’ll see two waves (one from each mic). 6. Measure the time difference (Δt) between the two waves. 7. Use the known distance (d) between the microphones and the time delay (Δt) to calculate the speed of sound using:
33
Equipment Needed
• Two microphones • Oscilloscope • Ruler or measuring tape (to measure distance between microphones) • Loud sound source (like a clap or a speaker)
34
Why Use an Oscilloscope?
• It lets you see the exact time when the sound hits each microphone. • You can measure the time delay precisely – sound is fast, so normal timers are not accurate enough.
35
What is the aim of the oscilloscope practical?
To measure the speed of sound in air.
36
What two devices detect the sound?
Two microphones
37
What device shows the sound signals
An oscilloscope
38
Speed of sound in air ≈
330–340 m/s
39
The first peak on each trace shows when..
the sound arrived.
40
What Are Electromagnetic (EM) Waves?
EM waves are transverse waves that transfer energy from one place to another without needing a medium (they can travel through a vacuum).
41
All EM waves travel at the..
same speed in a vacuum:
42
EM waves form a continuous spectrum, from..
radio waves (longest) to gamma rays (shortest).
43
Order of the EM Spectrum (from longest to shortest wavelength)
👉 Radio waves 👉 Microwaves 👉 Infrared 👉 Visible light 👉 Ultraviolet (UV) 👉 X-rays 👉 Gamma rays
44
EM waves form a continuous spectrum, from..
radio waves (longest) to gamma rays (shortest).
45
46
As you move down the list: Of em waves longet to shortes
Wavelength decreases • Frequency increases • Energy increases
47
Rabbits Mate In Very
Unusual eXpensive Gardens”
48
EM WAVES TRANSFER ENERGY
Electromagnetic (EM) waves carry energy from one place to another. The energy they transfer depends on their frequency and wavelength.
49
All EM waves transfer energy from..
a source to an absorber.
50
Example
51
The higher the frequency, the..
more energy the wave carries. That’s why gamma rays are the most energetic and dangerous.
52
Example
53
54
CHANGES IN ATOMS PRODUCE EM WAVES
EM waves are produced when changes occur in atoms or their nuclei.
55
Electrons changing energy levels
In an atom, electrons can move up energy levels when they absorb energy (e.g. from heat or electricity). • When electrons fall back down to a lower energy level, they release energy as an EM wave.
56
The type of EM wave depends on how much energy is
released
57
Nuclear changes produce EM waves
• When the nucleus of an atom changes, it can release gamma rays. • This happens during radioactive decay.
58
HOW EM WAVES ARE PRODUCED
CHANGES IN ATOMS PRODUCE EM WAVES 🔸 1. Electrons changing energy levels 🔸 2. Nuclear changes produce EM waves
59
What do EM waves transfer?
Energy from a source to an absorber.
60
What happens when EM waves are absorbed?
The absorber gains energy (often becomes hotter
61
What produces EM waves in atoms?
Electrons moving energy levels and changes in the nucleus.
62
Which em wave has the longest wave length
Radio waves
63
Which em wave has the shortest
Gamma waves
64
Radio Waves use why example
Use: Broadcasting radio & TV signals • Why? Can travel long distances & diffract around hills • Example: Car radios, walkie-talkies
65
Microwaves uses
Use 1: Satellite communication (e.g. phones, GPS) • Use 2: Cooking food (microwaves absorbed by water in food)
66
Infrared (IR) uses
• Use 1: Heaters & toasters • Use 2: Thermal imaging / night vision cameras • Use 3: Remote controls
67
Visible Light
• Use 1: Seeing • Use 2: Fibre optic communication • Use 3: Photography & cameras
68
Ultraviolet (UV) uses
• Use 1: Security pens / bank note checks • Use 2: Tanning beds • Use 3: Sterilising water (kills bacteria)
69
X-Rays uses
• Use 1: Medical imaging (bones & teeth) • Use 2: Airport security scanners
70
Gamma Rays uses
• Use 1: Sterilising medical equipment • Use 2: Treating cancer (radiotherapy) • Use 3: Detecting cancer
71
Is radio waves ionising
Radio waves are non-ionising – they’re safe.
72
What is bad about Ultraviolet (UV)
Can damage skin cells – wear sun cream.
73
Is x ray ionising
X-rays are ionising – can cause cancer, so only used when needed.
74
What can x rays cause
can cause cancer, so only used when needed.
75
Are Gamma Rays ionising
YES Most ionising EM wave – handled with care.
76
What is the most ionising EM wave
Gamma rays
77
What are radio waves used for?
Broadcasting and communication (TV, radio)
78
How does infrared cook food?
By heating the surface of the food
79
What is visible light used for in communication?
Fibre optics (light travels through glass fibres)
80
Which EM wave carries the most energy?
Gamma rays
81
X-RAYS IN MEDICINE – HOW THEY WORK
• X-rays pass through soft tissues (like skin and muscle) • X-rays are absorbed by dense materials (like bone and metal) • The X-ray detector shows a white area where X-rays were absorbed (e.g. bones)
82
X-ray Safety in Hospitals:
Patients are only exposed when needed • Radiographers stand behind a lead screen
83
GAMMA RAYS IN MEDICINE – HOW THEY WORK Cancer Treatment
• Gamma rays kill cancer cells by damaging their DNA • Focused on tumours with high precision • Healthy tissue can also be damaged, so: • Dose is controlled carefully
84
GAMMA RAYS IN MEDICINE – HOW THEY WORK Sterilising Medical Equipment:
Gamma rays kill bacteria and viruses • Used to sterilise: • Surgical instruments • Syringes • Bandages (especially those in sealed packaging)
85
Medical Tracers (Gamma Imaging):
• A gamma-emitting substance is swallowed or injected • Travels through the body • A gamma detector (camera) outside the body picks up the gamma rays
86
What Are Electromagnetic (EM) Waves?
• EM waves are transverse waves that transfer energy. • They all travel at the same speed in a vacuum (300,000,000 m/s). • The EM spectrum is arranged by increasing frequency and decreasing wavelength.
87
Ionising vs Non-ionising Radiation
Non ionising Radio, Microwaves, Infrared, Visible Ionising Ultraviolet, X-rays, Gamma rays
88
Dangers by Wave Type
Microwaves Infrared Radiation Visible Light Ultraviolet (UV X-rays Gamma Rays
89
Microwaves danger
Danger: Can heat human tissue deep inside the body
90
Infrared Radiation danger and why
Danger: Can burn the skin (causes skin damage through heating) • Why: It transfers heat energy
91
Visible Light danger
• Usually not dangerous unless very intense • High-intensity light (e.g., lasers) can damage the eyes
92
Ultraviolet (UV) danger protection
• Danger: • Ionising radiation • Damages skin cells → leads to sunburn • Increases risk of skin cancer • Can damage eyes and cause cataracts Protection: • Sunscreen • Sunglasses • Avoid strong sunlight
93
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X-rays danger and protection
• Highly penetrating and ionising • Can damage cells and DNA • May cause mutations → cancer • Protection in hospitals: • Use lead shielding (aprons/screens) • Limit exposure time
95
Gamma Rays danger
• Most dangerous EM wave • Very ionising • Can pass through the body and damage internal cells • Linked to cancer and cell death • Medical use: Can also be used to kill cancer cells in radiotherapy
96
Which EM waves are non-ionising?
Radio, Microwaves, Infrared, and Visible light
97
Why do radiographers wear lead protection?
To protect from ionising X-ray radiation

Physics Exam (6 decks)

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