IGCSEPhysicsEdexcelFlashcards3. WavesWaves & The Electromagnetic Spectrum

Waves & The Electromagnetic Spectrum (Edexcel IGCSE Physics)

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  • Define the term transverse wave.

    A transverse wave is a wave where the oscillations are at right angles (perpendicular) to the direction of energy transfer.

  • What are three examples of transverse waves?

    Examples of transverse waves include:

    • ripples on the surface of water

    • vibrations on a guitar string

    • S-waves (secondary seismic waves)

    • electromagnetic waves

  • Define the term longitudinal wave.

    A longitudinal wave is a wave where the oscillations are parallel to the direction of energy transfer.

  • What are three examples of longitudinal waves?

    Examples of longitudinal waves are:

    • sound waves

    • P-waves (primary seismic waves)

    • pressure waves in liquids or gases

  • True or False?

    Longitudinal waves can travel in a vacuum.

    False.

    Longitudinal waves require a medium to travel through, so they cannot travel in a vacuum since there are no particles in a vacuum.

  • What is the name for the part of a longitudinal wave where the particles are close together?

    In a longitudinal wave, the area where the particles are close together is called a compression.

  • What is the name for the part of a longitudinal wave where the particles are spaced far apart?

    In a longitudinal wave, the area where the particles are spaced far apart is called a rarefaction.

  • True or False?

    Visible light is an example of a transverse wave.

    True.

    Visible light is part of the electromagnetic spectrum. All electromagnetic waves are transverse waves.

  • True or False?

    Transverse waves can travel through a vacuum.

    True.

    Electromagnetic waves are transverse waves and they can travel through a vacuum. However, other types of transverse waves such as water waves and S-waves are mechanical waves that require a medium.

  • What is the key difference between transverse and longitudinal waves?

    The key difference between transverse and longitudinal waves is the direction of the vibrations with respect to the direction of the energy transfer. For transverse waves, the vibrations are perpendicular to the direction of energy transfer, while for longitudinal waves, the vibrations are parallel to the direction of energy transfer.

  • True or False?

    The highest point above the rest position of a transverse wave is called the peak of the wave.

    True.

    The highest point above the rest position of a transverse wave is called the peak or the crest of the wave.

  • What is the name of the lowest point below the rest position of a transverse wave?

    The name of the lowest point below the rest position of a transverse wave is the trough.

  • What type of wave is shown in the diagram?

    A green waveform moves up and down with peaks and troughs at 90 degrees to the wave's motion and energy transfer.

    The wave shown is a transverse wave because it oscillates at right angles of the direction of wave motion.

  • Sketch a longitudinal wave.

    Include the following labels:

    • direction of vibration

    • direction of energy transfer

    • compression

    • rarefaction

    A correctly labelled longitudinal wave is as follows:

    Vertical parallel lines are drawn across the page; some are further apart and labelled rarefaction, others are closer together and labelled compression. A double-headed arrow is labelled the direction of vibration and a single arrow through the centre of all the lines is labelled the direction of energy transfer.

  • Define the term amplitude.

    Amplitude is the distance from the central undisturbed position to the peak or trough of a wave.

  • What is the wavelength of a wave?

    The wavelength of a wave is the distance from one point on the wave to the same point on the next wave.

  • Define the term frequency.

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

  • Define the term wave speed.

    Wave speed is the speed at which a wave travels.

  • What is the symbol used for amplitude?

    The symbol used for amplitude is A.

  • What are the units of amplitude?

    The units of amplitude are metres (m).

  • Draw and label amplitude and wavelength on a diagram of a transverse wave.

    Amplitude is drawn from the central equilibrium position to the peak.

    Wavelength is drawn between consecutive peaks (or troughs).

    An oscillating waveform with peaks and troughs has a horizontal axis through the middle. Amplitude is labelled from the horizontal axis to a peak. Wavelength is labelled from one peak to the next.

  • Identify the wave property indicated by the arrow on the diagram.

    An oscillating wave with peaks and troughs is labelled with a double-headed arrow from the equilibrium point between a peak and a trough to the corresponding equilibrium point between a peak and a trough.

    The wave property indicated by the arrow on the diagram is time period, T.

  • What are the units of wave speed?

    The units of wave speed are metres per second (m/s).

  • What is the symbol for wave speed?

    The symbol for wave speed is v.

  • True or False?

    The symbol for frequency is lambda.

    False.

    The symbol for frequency is f.

  • True or False?

    The units of frequency are hertz (Hz).

    True.

    The units of frequency are hertz (Hz)

  • What are the units for wavelength?

    The units for wavelength are metres (m).

  • What is the symbol for wavelength?

    The symbol for wavelength is lambda, lambda.

  • State the wave equation in terms of wave speed.

    The wave equation in terms of wave speed is v space equals space f space cross times space lambda

    Where:

    • v = wave speed, measured in metres per second (m/s)

    • f = frequency, measured in hertz (Hz)

    • lambda = wavelength, measured in metres (m)

  • True or False?

    The wave speed equation in terms of wavelength is lambda space equals fraction numerator space f over denominator v end fraction.

    False.

    The wave speed equation in terms of wavelength is lambda space equals fraction numerator space v over denominator f end fraction

    Where:

    • lambda = wavelength, measured in metres (m)

    • v = wave speed, measured in metres per second (m/s)

    • f = frequency, measured in hertz (Hz)

  • True or False?

    The wave speed equation in terms of frequency is f space equals fraction numerator space v over denominator lambda end fraction.

    True.

    The wave speed equation in terms of frequency is f space equals fraction numerator space v over denominator lambda end fraction

    Where:

    • f = frequency, measured in hertz (Hz)

    • v = wave speed, measured in metres per second (m/s)

    • lambda = wavelength, measured in metres (m)

  • What is the equation linking time period, T and frequency, f?

    The equation linking time period, T and frequency, f is:

    T space equals space 1 over f

    Where:

    • T= time period, measured in seconds (s)

    • f = frequency, measured in hertz (Hz)

  • Define the Doppler effect.

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

  • What happens to the frequency of a siren as it moves past a stationary observer?

    The frequency of a siren decreases as it moves past a stationary observer.

  • How is the Doppler effect observed with galaxies?

    The Doppler effect, when observed with galaxies, shows that light waves have redshifted (wavelength increases) as the stars move away from Earth.

  • How do waves spread out from a stationary sound source?

    Waves from a stationary source sound spread out symmetrically.

  • True or False?

    The Doppler effect occurs when the wave source is stationary.

    False.

    The Doppler effect occurs when the source of the waves is moving (towards or away from an observer).

  • Describe the change in the wavelength of waves experienced by an observer positioned in front of a moving source?

    The wavelength of waves appears shorter for an observer positioned in front of a moving source.

  • Describe the change in the wavelength of waves experienced by an observer positioned behind a moving source.

    The wavelength of waves for an observer behind a moving source appears to get longer.

  • How is wave speed affected by the Doppler effect?

    Wave speed stays constant when the Doppler effect is observed.

  • State the feature of the diagram that identifies that the car is stationary when sound is emitted from the horn.

    A car is in the centre of three equally spaced concentric circles. A double-headed arrow between the second and third circles indicates this is the wavelength.

    The equally spaced wavefronts on the diagram identify that the car is stationary when sound is emitted from the horn.

  • What feature of the diagram shows that the observer hears a higher pitch as the source moves towards them?

    A moving source is at the centre of four concentric circles. The circles are not evenly spaced. The circles are closer together on the right side next to the stationary observer.

    The feature of the diagram that shows that the observer hears a higher pitch as the source moves towards them is that the wavefronts are closer together next to the observer.

  • True or False?

    The electromagnetic spectrum is arranged in a specific order based on the wavelengths or frequencies.

    True.

    The electromagnetic spectrum is arranged in a specific order based on the wavelengths or frequencies.

  • What is the order of the electromagnetic spectrum from longest to shortest wavelength?

    The order of the electromagnetic spectrum from longest to shortest wavelength is:

    • Radio waves

    • Microwaves

    • Infrared

    • Visible light

    • Ultraviolet

    • X-rays

    • Gamma rays

  • What are the properties of electromagnetic waves?

    All electromagnetic waves share the following properties:

    • transverse

    • can travel through a vacuum

    • travel at the same speed in a vacuum

    • form a continuous spectrum

  • Define the term electromagnetic waves.

    Electromagnetic waves are transverse waves with oscillating electric and magnetic fields that transfer energy from the source of the waves to an absorber.

  • True or False?

    The speed of electromagnetic waves in air is the same as in a vacuum.

    True.

    The speed of electromagnetic waves in air can be approximated to the speed of light in a vacuum because the difference in speed is so small.

  • What is the relationship between the frequency of electromagnetic waves and the energy they transfer?

    The higher the frequency, the higher the energy of the radiation, and vice versa.

  • What is a mnemonic for remembering the correct order of radiation in the electromagnetic spectrum?

    One possible mnemonic for remembering the correct order of radiation in the electromagnetic spectrum is:

    Raging Martians Invaded Venus Using X-ray Guns.

  • Identify using the diagram the electromagnetic radiation type with the shortest wavelength.

    An oscillating wave decreases in wavelength as it moves from left to right. Labels below the waveform also moving from left to right are radio waves, microwaves, infrared, visible light, ultraviolet, x-rays and gamma rays.

    The electromagnetic radiation type with the shortest wavelength is gamma rays.

  • Identify using the diagram the electromagnetic radiation type with the highest frequency.

    An oscillating wave decreases in wavelength as it moves from left to right. Labels below the waveform also moving from left to right are radio waves, microwaves, infrared, visible light, ultraviolet, x-rays and gamma rays.

    The electromagnetic radiation type with the highest frequency is gamma rays.

  • Identify using the diagram the electromagnetic radiation type with the lowest frequency.

    An oscillating wave decreases in wavelength as it moves from left to right. Labels below the waveform also moving from left to right are radio waves, microwaves, infrared, visible light, ultraviolet, x-rays and gamma rays.

    The electromagnetic radiation type with the lowest frequency is radio waves.

  • Define the term fluorescence.

    Fluorescence is the process where certain substances absorb ultraviolet light and re-emit it as visible light, causing them to glow.

  • What is the main application of radio waves?

    The main application of radio waves is in wireless communications.

  • What are the two main applications of microwaves?

    The two main applications of microwaves are:

    • heating food

    • wireless communications

  • True or False?

    Night vision cameras use infrared radiation.

    True.

    One application of infrared radiation is night vision cameras.

  • True or False?

    Gamma radiation is used in fibre optic communications.

    False.

    Infrared and visible light are used in optic fibre communications. Gamma rays are used for sterilising medical equipment and treating cancer.

  • True or False?

    Sterilising water and detecting fake bank notes are two applications of X-rays.

    False.

    Sterilising water and detecting fake bank notes are two applications of ultraviolet radiation (UV). X-rays are used for imaging in medicine, dentistry, airport security and industry.

  • True or False?

    Visible light is the only part of the electromagnetic spectrum that human eyes can see.

    True.

    Human eyes can only detect wavelengths of electromagnetic radiation in the visible light section of the electromagnetic spectrum.

  • True or False?

    Remote controls are one application of ultraviolet radiation.

    False.

    Ultraviolet radiation carries too much energy and would be harmful if used for this purpose. Remote controls are one application of infrared radiation.

  • State the type of radiation used in the device in the diagram.

    A potato is sitting on a tray in a machine with a translucent door, an emitter at the top and buttons on the side.

    The device in the diagram is a microwave oven and uses microwaves.

  • True or False?

    As the frequency of electromagnetic waves increases, so does the energy and the danger associated with them.

    True.

    As the frequency of electromagnetic waves increases, the energy they transfer increases, and therefore so does the danger associated with them.

  • What is the main danger associated with ultraviolet, X-rays, and gamma rays?

    Ultraviolet, X-rays, and gamma rays can all ionise atoms, which can damage cells and cause mutations, which can lead to cancer.

  • True or False?

    Radio waves are known to be harmful to humans.

    False.

    There are no known harmful effects of radio waves.

  • True or False?

    Microwaves can be harmful to humans.

    True.

    Microwaves can be harmful to humans in high levels of exposure, because higher-frequency microwaves cause internal heating.

  • True or False?

    Mobile phones emit microwave radiation.

    True.

    Mobile phones do emit microwave radiation, but only at low energies which are not known to cause any harm.

  • True or False?

    Ultraviolet radiation can be harmful to humans.

    True.

    Ultraviolet radiation can cause sunburn, eye damage and skin cancer.

  • True or False?

    X-rays and gamma rays can be harmful to humans.

    True.

    X-rays and gamma rays (and UV) are ionising radiation which can remove electrons from atoms, causing damage to DNA which can lead to cell and tissue damage, mutations and cancer.

  • True or False?

    Sunscreen absorbs ultraviolet light, preventing it from damaging the skin.

    True.

    Sunscreen absorbs ultraviolet light, preventing it from damaging the skin.

  • True or False?

    Ionising forms of electromagnetic radiation have a higher frequency than visible light.

    True.

    The ionising forms of electromagnetic radiation are ultraviolet, X-rays and gamma rays, all of which have higher frequencies than visible light.

  • True or False?

    The longer the wavelength, the more ionising the electromagnetic radiation.

    False.

    The shorter the wavelength (and therefore, the higher the frequency), the more ionising the electromagnetic radiation.

  • State the purpose of the device in the image.

    A blue sealed badge with a photographic plate inside that can be attached with a safety pin.

    The device in the image is a radiation badge and its purpose is to measure a person's exposure to radiation.

1. Forces & Motion
2. Electricity
3. Waves
4. Energy Resources & Energy Transfers
5. Solids, Liquids & Gases
6. Magnetism & Electromagnetism
7. Radioactivity & Particles
8. Astrophysics