P6 Redo Flashcards
What do waves transfer without transferring any matter?
Energy
Waves transfer energy from one place to another while the particles of the medium stay in the same place.
What is a medium in the context of waves?
The substance through which the wave travels (e.g. water, air)
A medium is the material that carries the wave.
In transverse waves, how are the vibrations oriented relative to the direction of energy transfer?
Perpendicular (at right angles)
Examples include light waves and ripples on water.
What is an example of a transverse wave?
Light
Other examples include ripples on water and waves on a string.
In longitudinal waves, how are the vibrations oriented relative to the direction of energy transfer?
In the same direction
An example of a longitudinal wave is a sound wave.
What are the two key components of longitudinal waves?
Compressions and rarefactions
Compressions are where particles are squished together, rarefactions are where they spread out.
Define amplitude in the context of waves.
The maximum displacement from the undisturbed (rest) position
Amplitude indicates how tall the wave is from its rest position.
What is wavelength?
The distance between one point on a wave and the same point on the next wave
For example, the distance from one trough to the next trough.
What is frequency and how is it measured?
The number of complete waves passing a point each second, measured in hertz (Hz)
1 Hz equals 1 wave per second.
What does the period of a wave represent?
The amount of time it takes for one complete wave to pass a certain point
The period is the inverse of frequency.
True or False: Waves carry matter along with energy.
False
Waves transfer energy without transferring matter.
Fill in the blank: The particles of the medium ________ as the wave travels.
vibrate
Give two examples of longitudinal waves.
Sound waves
Other examples can include pressure waves in fluids.
What is the formula to calculate the period of a wave from its frequency?
T = 1/f
T is the period in seconds, and f is the frequency in Hertz.
If a wave has a frequency of 2 Hz, what is its period?
0.5 s
Calculated using T = 1/f, where f = 2 Hz.
What is the wave speed equation?
Wave speed (m/s) = frequency (Hz) x wavelength (m)
This equation applies to all types of waves.
How do you find the wavelength of a radio wave with a frequency of 12,000,000 Hz?
Wavelength = (3 × 10^8) ÷ (12,000,000) = 25 m
The speed of radio waves in air is approximately 3 × 10^8 m/s.
What equipment is used to measure the speed of sound?
Oscilloscope and microphones
An oscilloscope displays waves visually, while microphones capture sound waves.
What is the first step to measure the speed of sound using an oscilloscope?
Connect two microphones to an oscilloscope
This setup allows you to visualize the sound waves captured by the microphones.
What should you do after connecting the microphones to the oscilloscope?
Connect a signal generator to a speaker
This generates sound waves at a set frequency.
What is the purpose of adjusting the distance between the microphones?
To measure one wavelength
The distance between the microphones should equal one wavelength when the waves line up again.
How do you calculate the speed of sound using the oscilloscope setup?
Use the formula v = fλ
v is the speed, f is the frequency set on the signal generator, and λ is the measured wavelength.
What is the approximate speed of sound in air?
330 m/s
This value serves as a reference to check experimental results.
Fill in the blank: The wave speed is how fast the wave is _______.
moving
True or False: The wave speed indicates how fast energy is being transferred through the medium.
True
If a wave has a speed of 0.15 m/s and a wavelength of 7.5 cm, how do you calculate its frequency?
Use the formula f = v/λ
Convert 7.5 cm to meters for calculation.
What is the first step in measuring the speed of water ripples using a ripple tank?
Attach a signal generator to the ripple tank dipper.
How do you find the frequency of the waves created in a ripple tank?
Count the number of ripples that pass a point in 10 seconds and divide by 10.
What can be used to create shadows of the ripples on a screen?
A lamp.
What does the distance between each shadow line represent?
One wavelength.
How do you measure the wavelength accurately using shadow lines?
Measure the distance across 10 gaps between the shadow lines and divide by 10.
What equation is used to calculate the wave speed?
v = f.
Why is the ripple tank setup suitable for investigating waves?
It allows you to measure the wavelength without disturbing the waves.
What is the first step in using the wave equation for waves on strings?
Set up the equipment shown.
What does the vibration generator do in a wave-on-string experiment?
Vibrates at a fixed frequency set by the signal generator.
How can you measure the wavelength of waves on a string?
Count how many wavelengths are on the string and divide the length of the whole vibrating string by the number of wavelengths.
If there are 3 loops on the string, how many wavelengths are there?
One-and-a-half wavelengths.
How do you find the speed of the wave on a string?
Use the equation v = fr.
Why is the setup for waves on a string suitable for investigation?
It’s easy to see and measure the wavelength and frequency.
Fill in the blank: You can take a photo of the shadows and ruler to find the wavelength from the _______.
photo.
True or False: It is necessary to have a whole number of wavelengths on the string for measurement.
False.
What is the benefit of conducting the experiment in a darkened room?
It enhances the visibility of the shadows cast by the ripples.
What types of waves are mentioned as easy to make and observe?
- Sound waves
- Ripples
- Waves on strings
What happens when a wave crosses a boundary between two materials?
It can change direction.
This phenomenon is known as refraction.
What is the term for the change in direction of a wave as it crosses a boundary?
Refraction.
Waves are only refracted if they meet the boundary at an angle.
What determines how much a wave is refracted?
The two materials it’s passing between.
Different materials have different refractive indices.
What do ray diagrams represent?
The path of a wave.
Rays are straight lines that show the direction a wave is travelling in.
What is the ‘normal’ in the context of ray diagrams?
A line at right angles to the boundary.
‘Normal’ indicates a 90-degree angle with respect to the boundary.
What is the angle between the incident ray and the normal called?
Angle of incidence.
This angle is crucial for determining how the wave will refract.
What is the angle called that is formed between the refracted ray and the normal?
Angle of refraction.
This angle helps in understanding the degree of bending of the wave.
Fill in the blank: The _______ ray is the ray that meets the boundary at the normal.
incident
It is essential for calculating the angles of incidence and refraction.
True or False: All electromagnetic waves behave the same way when crossing boundaries.
True.
This includes various types such as visible light, infrared, and others.
What is the first step in constructing a ray diagram for a refracted light ray?
Draw the boundary between the two materials.
This sets the stage for the subsequent steps in the diagram.
How do you measure the angle of incidence in a ray diagram?
Use a protractor.
Accurate measurements are necessary for precise ray diagrams.
What is the significance of understanding refraction?
It is a common behavior of waves.
Mastery of this concept is essential before advancing to more complex topics.
What are electromagnetic (EM) waves?
Transverse waves that transfer energy from a source to an absorber.
What is an example of a source of electromagnetic waves?
A camp fire.
What type of EM wave is emitted by a camp fire?
Infrared radiation.
How do infrared waves affect objects?
They are absorbed by objects, transferring energy to their thermal energy stores.
What is the speed of all EM waves in air or a vacuum?
They all travel at the same speed, which is much faster than the speed of sound in air.
How do sound waves compare to light waves in terms of wavelength and frequency?
Sound waves have a much bigger wavelength and a much lower frequency than light waves.
What is meant by a continuous spectrum of EM waves?
EM waves vary in wavelength and frequency, with every wavelength within a certain range.
How is the electromagnetic spectrum divided?
Into seven groups based on wavelength and frequency: Radio, Micro, Infrared, Visible, Red light, Ultraviolet, X-rays, Gamma rays.
Which part of the EM spectrum can humans detect?
Visible light.
What can cause the absorption or production of EM radiation?
Changes in atoms and their nuclei.
What kind of changes in atoms can produce gamma rays?
Changes in the nucleus of an atom.
What happens when electrons move between energy levels in atoms?
It produces or absorbs a different frequency of EM wave.
What is a mnemonic to remember the order of EM waves?
‘Rock Music Is Very Useful for eXperiments with Goats’.
Fill in the blank: The type of electromagnetic wave that has the lowest frequency is _______.
[Radio waves]
Fill in the blank: The section of the electromagnetic spectrum that humans can see is _______.
[Visible light]
What are radio waves primarily used for?
Communication
Radio waves are essential for sending signals for radio and IV.
What type of radio waves are used for FM radio and TV?
Very short wavelength signals
These signals must be in direct sight of the receiver.
True or False: Very short wavelength radio waves can travel very far.
False
They cannot travel very far and need a direct line of sight.
What can longer wavelength radio waves do?
Travel further and send signals around the world
Longer wavelengths are more effective for long-distance communication.
How do satellites communicate using microwaves?
A signal is sent to a satellite dish which relays it back to Earth
This is used in satellite TV and satellite phones.
Fill in the blank: Microwave ovens use _______ to cook food.
microwaves
Microwaves heat food by being absorbed by water molecules.
What happens to water molecules in food when microwaves are absorbed?
They heat up
This heating causes the entire food to cook quickly.
What does infrared (IR) radiation do?
Is emitted by all objects and increases with temperature
Hotter objects emit more IR radiation.
How does infrared radiation warm an object?
Energy is transferred to the object’s thermal energy store
This causes the object to warm up.
Name one use of infrared cameras.
Detect IR radiation and create pictures
This helps identify energy loss in buildings.
What is one way infrared radiation is used in heating?
Electric heaters release IR radiation to warm a room
IR radiation is effective for heating.
True or False: Infrared radiation can only be used for cooking.
False
Infrared radiation can also be used for heating and detecting objects.
What does the color detected by infrared cameras indicate?
Different amounts of IR radiation
Redder colors indicate higher levels of detected IR radiation.
Fill in the blank: Microwaves are handy for more than _______.
cooking chips
They are also used in communication and other technologies.
What are optical fibres?
Thin glass or plastic tubes that can carry data over long distances
Often used in telecommunications to send information to devices like telephones or computers.
How do optical fibres send information?
As light rays that bounce back and forth along the fibre
This method allows for efficient data transmission over long distances.
What effect does ultraviolet (UV) radiation have on some materials?
It causes them to absorb UV light and emit visible light
This property is utilized in energy-efficient lighting and security pens.
What is one use of UV radiation in lighting?
To produce visible light in energy-efficient lights
This process involves UV light being converted to visible light.
What can security pens do under UV light?
Their ink will glow, making it visible only under UV light
This feature helps in identifying stolen property.
What natural source produces ultraviolet radiation?
The Sun
UV radiation from the Sun is responsible for suntans.
What is a risk of using UV lamps for tanning?
They can be dangerous
Overexposure to UV radiation can lead to skin damage.
What is one property of X-rays?
They pass easily through flesh but not through bones or metal
This property allows for their use in medical imaging.
How can X-rays be used in medicine?
To create images for checking broken bones and to treat cancer
X-rays can kill cancer cells when aimed correctly.
What is a function of gamma rays in medicine?
They can kill cells and sterilize medical equipment
Gamma rays are effective at removing germs from instruments.
What is a use of gamma rays as medical tracers?
To track how they move around the body
This helps doctors assess organ function.
True or False: X-rays can be used to treat cancer.
True
X-rays target cancer cells to kill them.
Fill in the blank: Ultraviolet radiation can give you a _______.
suntan
This occurs due to the skin’s reaction to UV exposure.
List two uses of X-rays.
- To create X-ray images for checking broken bones
- To treat cancer by targeting cancer cells
These applications highlight the importance of X-rays in medical diagnostics and treatment.
What does the amount of infrared radiation an object gives out depend on?
It depends on its temperature and its surface characteristics.
What surface characteristics affect infrared radiation emission?
Roughness or shininess and color.
What is a Leslie cube?
A hollow, metal cube used to investigate infrared radiation emission.
What surfaces are used on the four faces of a Leslie cube?
- Matt black paint
- Matt white paint
- Shiny metal
- Dull metal
What is the first step in investigating emission with a Leslie cube?
Place an empty Leslie cube on a heat-proof mat.
How far should the infrared detector be held from the Leslie cube’s vertical face?
10 cm away.
What should be recorded during the experiment with the Leslie cube?
The amount of IR radiation detected by the infrared detector.
What surface is expected to radiate more infrared radiation, black or white?
The black surface is expected to radiate more IR radiation than the white one.
Which types of surfaces are expected to emit more infrared radiation?
Matt surfaces should give off more than shiny ones.
What should be done to check the results of the infrared radiation experiment?
Repeat the experiment.
True or False: The face that had the highest reading is giving off the least IR radiation.
False.
Fill in the blank: The best emitter of infrared radiation between a black surface and a white surface is _______.
black surface.
Fill in the blank: The best emitter of infrared radiation between a shiny surface and a matt surface is _______.
matt surface.
What is a practical way to feel which surface is giving off more infrared radiation?
Place your hand near each surface without touching it.
What is the purpose of the Melting Wax Trick in the experiment?
To investigate infrared radiation absorption by different materials
The experiment uses metal plates with different colored surfaces to demonstrate varying absorption rates.
What equipment is used in the Melting Wax Trick experiment?
Bunsen burner, heat-proof mat, metal plates, wax, metal balls, detector
Each component plays a crucial role in observing the effects of infrared radiation on the wax.
What happens to the candle wax during the experiment?
It absorbs thermal energy and starts to melt
This melting causes the attached metal balls to fall.
How is the setup for the experiment arranged?
One plate has a black back and the other a white back, both facing the flame
They must be the same distance from the flame for a fair test.
What indicates which plate is better at absorbing infrared radiation?
The ball that falls first
The ball on the black surface should fall first, indicating better absorption.
Fill in the blank: The black surface was better at absorbing _______ than the white surface.
infrared radiation
True or False: The experiment shows that color affects the absorption of infrared radiation.
True
The results demonstrate that darker colors absorb more infrared radiation.
What is a key factor in making the experiment a fair test?
Both plates must be the same distance from the flame
This ensures that both plates are exposed to the same amount of infrared radiation.
What does the experiment demonstrate about the relationship between surface color and infrared absorption?
Darker surfaces absorb more infrared radiation than lighter surfaces
This principle is applicable in various scientific and practical contexts.
What can EM radiation do when it enters living tissue?
It can be dangerous
High frequency waves like UV, X-rays, and gamma rays can cause significant damage.
What are the effects of UV radiation on the skin?
Damages surface cells, leads to sunburn, causes skin to age faster
More serious effects include blindness and a higher risk of skin cancer.
What type of radiation are X-rays and gamma rays classified as?
Ionising radiation
They can knock electrons off atoms, potentially destroying cells or mutating genes.
What is the unit used to measure radiation dose?
Sieverts
Millisieverts (mSv) are often used for smaller doses, where 1000 mSv = 1 Sv.
How does the risk of radiation harm vary?
It depends on the total amount of radiation absorbed and the type of radiation
Different types of radiation have different harmful effects.
What is the radiation dose received by the head during a CT scan?
2.0 mSv
This is significantly lower than the dose received by the chest.
What is the radiation dose received by the chest during a CT scan?
8.0 mSv
This is four times larger than the dose for the head scan.
True or False: A CT scan on the chest poses a lower risk of harm than a CT scan on the head.
False
The chest scan has a higher radiation dose, making it four times more likely to cause harm.
Fill in the blank: A small dose of radiation every now and then is very _______.
low risk
This is why X-rays are generally not a cause for concern.
List two serious effects of UV radiation exposure.
- Blindness
- Higher risk of skin cancer
