Define transverse wave .

A transverse wave is a wave that vibrates or oscillates perpendicular to the direction of energy transfer.

Define longitudinal wave .

A longitudinal wave is a wave that vibrates or oscillates parallel to the direction of energy transfer.

What are the highest and lowest points of a transverse wave called?

The highest point is called a peak (or crest ); the lowest point is called a trough .

What are the two key features of a longitudinal wave , and how is each one described?

Compressions , where points are close together, and rarefactions , where points are spaced apart.

Electromagnetic waves are transverse waves that can travel through solids, liquids, gases and in a ______ .

Electromagnetic waves are transverse waves that can travel through solids, liquids, gases and in a vacuum .

True or False? Sound waves can travel through a vacuum.

False. Sound waves are longitudinal waves that need particles to vibrate; since a vacuum has no particles, sound cannot travel through it.

What do all waves transfer, and what do they not transfer?

All waves transfer energy and information , but they do not transfer matter .

Amplitude is the distance from the undisturbed position to the peak or trough of a wave. It is given the symbol A and measured in metres (m) .

Wavelength is the distance from one point on a wave to the same point on the next wave. It is given the symbol λ and measured in metres (m) .

Frequency is the number of waves passing a point in a second. It is given the symbol f and measured in hertz (Hz) .

What is meant by the time period of a wave, and what is its unit?

The time period is the time taken for a single wave to pass a point. It is given the symbol T and measured in seconds (s) .

What does the spacing between wavefronts represent, and what does it mean if the wavefronts are close together?

The spacing between wavefronts represents the wavelength . Wavefronts close together mean a short wavelength ; wavefronts far apart mean a long wavelength .

In a transverse wave , wavelength can be measured from one ______ to the next, whereas in a longitudinal wave it is measured from the centre of one ______ to the next.

In a transverse wave , wavelength can be measured from one peak to the next, whereas in a longitudinal wave it is measured from the centre of one compression to the next.

True or False? Waves with a higher frequency transfer a greater amount of energy.

True. A higher frequency means more waves pass a point each second, so more energy is transferred.

The wave speed equation states that wave speed = frequency × ______ .

The wave speed equation states that wave speed = frequency × wavelength .

True or False? The wave equation v = f × λ only applies to electromagnetic waves.

False. The wave equation applies to all types of waves , including sound waves and electromagnetic waves .

Why must a frequency given in kHz be converted before it is used in the wave speed equation?

The wave speed equation requires frequency in hertz (Hz) , and 1 kHz = 1000 Hz, so the kHz value must be converted first.

Define the Doppler effect .

The Doppler effect is the apparent change in observed wavelength and frequency of a wave emitted by a moving source relative to an observer.

How does the pitch of an ambulance siren change to a stationary observer as the ambulance passes them?

The pitch goes from high (high frequency) to low (low frequency) as the ambulance passes.

Why does light from distant galaxies appear redder (longer wavelength) to an observer on Earth?

Because the galaxies are moving away from Earth, the light waves appear stretched , increasing the observed wavelength.

How do waves spread out from a stationary source?

They spread out symmetrically in all directions.

To an observer in front of a moving wave source, the wavelength appears ______ and the frequency appears ______ .

To an observer in front of a moving wave source, the wavelength appears shorter and the frequency appears higher .

True or False? An observer behind a moving source of waves detects a longer wavelength and lower frequency.

True. Behind the source, the waves appear stretched apart , so the wavelength appears longer and the frequency appears lower.

When can the Doppler effect be observed?

Whenever the source of waves is moving relative to an observer.

Define the electromagnetic spectrum .

The continuous range of electromagnetic waves, ordered by wavelength and frequency: radio , microwave , infrared , visible , ultraviolet , X-ray and gamma ray .

What three properties do all electromagnetic waves share?

All electromagnetic waves are transverse , can travel through a vacuum (free space), and travel at the same speed in free space.

Radio waves have the ______ wavelength and the lowest frequency of all electromagnetic waves.

Radio waves have the longest wavelength and the lowest frequency of all electromagnetic waves.

True or False? Wavelength and frequency of electromagnetic waves are directly proportional to each other.

False. They are inversely proportional : as wavelength increases, frequency decreases, and vice versa.

Define visible light , in terms of the electromagnetic spectrum.

The only part of the electromagnetic spectrum detectable by the human eye .

In the visible light spectrum, which colour has the longest wavelength and which has the shortest?

Red light has the longest wavelength (lowest frequency); violet light has the shortest wavelength (highest frequency).

What are the main uses of radio waves?

Broadcasting and communications , including radios, air traffic communication and mobile phone communication.

What are the main uses of microwaves?

Wireless communication (e.g. mobile phones) and satellite transmissions ; at very high intensities, microwaves are used to heat food in a microwave oven .

Give two uses of infrared radiation.

Thermal imaging (e.g. security cameras to see people in the dark), TV remote controls , and transporting signals through optical fibre cables .

______ light is the only part of the electromagnetic spectrum detectable by the human eye, and is used for vision and photography.

Visible light is the only part of the electromagnetic spectrum detectable by the human eye, and is used for vision and photography.

Define fluorescence .

The process in which a substance absorbs ultraviolet radiation and re-emits it as visible light , causing it to glow.

Give a security use of fluorescence.

Marking items, such as banknotes , with special ink that glows under ultraviolet light.

Define sterilising , as used with gamma radiation.

Killing bacteria and other microorganisms; gamma rays are used to sterilise food and medical equipment.

True or False? Optical fibre communication is a use of visible light.

False. Optical fibre communication is a use of infrared radiation; visible light's uses are vision and photography.

What harm can excessive exposure to microwaves cause?

Heat damage to internal organs , due to internal heating of body tissue.

What harm can excessive exposure to ultraviolet radiation cause?

Damage to skin cells, causing sunburn , and blindness .

What harm can excessive exposure to gamma rays and X-rays cause?

Cell death and cell mutations , which can cause cancer .

As the ______ of electromagnetic waves increases, so does their energy; beyond the visible part of the spectrum this becomes large enough to ionise atoms.

As the frequency of electromagnetic waves increases, so does their energy; beyond the visible part of the spectrum this becomes large enough to ionise atoms.

How do microwave ovens prevent microwave radiation from escaping?

Metal walls and a metal grid in the glass door contain the microwaves.

How is skin protected from infrared radiation damage?

Wearing protective clothing , such as gloves, prevents the skin from feeling the heat.

How are the eyes and skin protected from ultraviolet radiation?

Sunglasses absorb ultraviolet radiation to protect the eyes; sunscreen absorbs ultraviolet radiation to protect the skin.

Define a radiation badge .

A device worn by people who work closely with radiation, such as radiographers, to monitor and measure their level of radiation exposure.

True or False? The danger associated with electromagnetic waves increases as their frequency increases.

True. Higher-frequency electromagnetic waves carry more energy, making them more ionising and more hazardous.

IGCSEPhysicsEdexcelPhysics (Modular)Unit 2Flashcards5. WavesWaves & The Electromagnetic Spectrum

Waves & The Electromagnetic Spectrum (Edexcel IGCSE Physics (Modular): Unit 2): Flashcards

Exam code: 4XPH1

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FrontTransverse & Longitudinal Waves
Define transverse wave.

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Cards in this collection (53)

Define transverse wave.
A transverse wave is a wave that vibrates or oscillates perpendicular to the direction of energy transfer.
Define longitudinal wave.
A longitudinal wave is a wave that vibrates or oscillates parallel to the direction of energy transfer.
What are the highest and lowest points of a transverse wave called?
The highest point is called a peak (or crest); the lowest point is called a trough.
What are the two key features of a longitudinal wave, and how is each one described?
Compressions, where points are close together, and rarefactions, where points are spaced apart.
Electromagnetic waves are transverse waves that can travel through solids, liquids, gases and in a ______.
Electromagnetic waves are transverse waves that can travel through solids, liquids, gases and in a vacuum.
True or False?
Sound waves can travel through a vacuum.
False.
Sound waves are longitudinal waves that need particles to vibrate; since a vacuum has no particles, sound cannot travel through it.
What do all waves transfer, and what do they not transfer?
All waves transfer energy and information, but they do not transfer matter.
Define amplitude.
Amplitude is the distance from the undisturbed position to the peak or trough of a wave. It is given the symbol A and measured in metres (m).
Define wavelength.
Wavelength is the distance from one point on a wave to the same point on the next wave. It is given the symbol λ and measured in metres (m).
Define frequency.
Frequency is the number of waves passing a point in a second. It is given the symbol f and measured in hertz (Hz).
What is meant by the time period of a wave, and what is its unit?
The time period is the time taken for a single wave to pass a point. It is given the symbol T and measured in seconds (s).
What does the spacing between wavefronts represent, and what does it mean if the wavefronts are close together?
The spacing between wavefronts represents the wavelength. Wavefronts close together mean a short wavelength; wavefronts far apart mean a long wavelength.
In a transverse wave, wavelength can be measured from one ______ to the next, whereas in a longitudinal wave it is measured from the centre of one ______ to the next.
In a transverse wave, wavelength can be measured from one peak to the next, whereas in a longitudinal wave it is measured from the centre of one compression to the next.
True or False?
Waves with a higher frequency transfer a greater amount of energy.
True.
A higher frequency means more waves pass a point each second, so more energy is transferred.
State the wave speed equation, and define each term with its unit.
$v = f \times λ$
Where v = wave speed (m/s), f = frequency (Hz), λ = wavelength (m).
State the equation linking frequency and time period, and define each term with its unit.
$f = \frac{1}{T}$
Where f = frequency (Hz), T = time period (s).
The wave speed equation states that wave speed = frequency × ______.
The wave speed equation states that wave speed = frequency × wavelength.
A sound wave travels at 330 m/s and has a frequency of 10 000 Hz. Calculate its wavelength.
$λ = \frac{v}{f} = \frac{330}{10000} = 0.033 m$
Radio waves have a frequency of 200 kHz and a wavelength of 1500 m. Calculate their speed, stating an appropriate unit.
$v = f \times λ = 200000 \times 1500 = 3 \times 10^{8} m / s$
True or False?
The wave equation v = f × λ only applies to electromagnetic waves.
False.
The wave equation applies to all types of waves, including sound waves and electromagnetic waves.
Why must a frequency given in kHz be converted before it is used in the wave speed equation?
The wave speed equation requires frequency in hertz (Hz), and 1 kHz = 1000 Hz, so the kHz value must be converted first.
Define the Doppler effect.
The Doppler effect is the apparent change in observed wavelength and frequency of a wave emitted by a moving source relative to an observer.
How does the pitch of an ambulance siren change to a stationary observer as the ambulance passes them?
The pitch goes from high (high frequency) to low (low frequency) as the ambulance passes.
Why does light from distant galaxies appear redder (longer wavelength) to an observer on Earth?
Because the galaxies are moving away from Earth, the light waves appear stretched, increasing the observed wavelength.
How do waves spread out from a stationary source?
They spread out symmetrically in all directions.
To an observer in front of a moving wave source, the wavelength appears ______ and the frequency appears ______.
To an observer in front of a moving wave source, the wavelength appears shorter and the frequency appears higher.
True or False?
An observer behind a moving source of waves detects a longer wavelength and lower frequency.
True.
Behind the source, the waves appear stretched apart, so the wavelength appears longer and the frequency appears lower.
When can the Doppler effect be observed?
Whenever the source of waves is moving relative to an observer.
Define the electromagnetic spectrum.
The continuous range of electromagnetic waves, ordered by wavelength and frequency: radio, microwave, infrared, visible, ultraviolet, X-ray and gamma ray.
What three properties do all electromagnetic waves share?
All electromagnetic waves are transverse, can travel through a vacuum (free space), and travel at the same speed in free space.
Radio waves have the ______ wavelength and the lowest frequency of all electromagnetic waves.
Radio waves have the longest wavelength and the lowest frequency of all electromagnetic waves.
Which type of electromagnetic wave has the shortest wavelength and the highest frequency?
Gamma rays.
True or False?
Wavelength and frequency of electromagnetic waves are directly proportional to each other.
False.
They are inversely proportional: as wavelength increases, frequency decreases, and vice versa.
Define visible light, in terms of the electromagnetic spectrum.
The only part of the electromagnetic spectrum detectable by the human eye.
In the visible light spectrum, which colour has the longest wavelength and which has the shortest?
Red light has the longest wavelength (lowest frequency); violet light has the shortest wavelength (highest frequency).
What are the main uses of radio waves?
Broadcasting and communications, including radios, air traffic communication and mobile phone communication.
What are the main uses of microwaves?
Wireless communication (e.g. mobile phones) and satellite transmissions; at very high intensities, microwaves are used to heat food in a microwave oven.
Give two uses of infrared radiation.
Thermal imaging (e.g. security cameras to see people in the dark), TV remote controls, and transporting signals through optical fibre cables.
______ light is the only part of the electromagnetic spectrum detectable by the human eye, and is used for vision and photography.
Visible light is the only part of the electromagnetic spectrum detectable by the human eye, and is used for vision and photography.
Define fluorescence.
The process in which a substance absorbs ultraviolet radiation and re-emits it as visible light, causing it to glow.
Give a security use of fluorescence.
Marking items, such as banknotes, with special ink that glows under ultraviolet light.
Define sterilising, as used with gamma radiation.
Killing bacteria and other microorganisms; gamma rays are used to sterilise food and medical equipment.
True or False?
Optical fibre communication is a use of visible light.
False.
Optical fibre communication is a use of infrared radiation; visible light's uses are vision and photography.
What harm can excessive exposure to microwaves cause?
Heat damage to internal organs, due to internal heating of body tissue.
What harm can excessive exposure to infrared radiation cause?
Burns to the skin.
What harm can excessive exposure to ultraviolet radiation cause?
Damage to skin cells, causing sunburn, and blindness.
What harm can excessive exposure to gamma rays and X-rays cause?
Cell death and cell mutations, which can cause cancer.
As the ______ of electromagnetic waves increases, so does their energy; beyond the visible part of the spectrum this becomes large enough to ionise atoms.
As the frequency of electromagnetic waves increases, so does their energy; beyond the visible part of the spectrum this becomes large enough to ionise atoms.
How do microwave ovens prevent microwave radiation from escaping?
Metal walls and a metal grid in the glass door contain the microwaves.
How is skin protected from infrared radiation damage?
Wearing protective clothing, such as gloves, prevents the skin from feeling the heat.
How are the eyes and skin protected from ultraviolet radiation?
Sunglasses absorb ultraviolet radiation to protect the eyes; sunscreen absorbs ultraviolet radiation to protect the skin.
Define a radiation badge.
A device worn by people who work closely with radiation, such as radiographers, to monitor and measure their level of radiation exposure.
True or False?
The danger associated with electromagnetic waves increases as their frequency increases.
True.
Higher-frequency electromagnetic waves carry more energy, making them more ionising and more hazardous.

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