Electromagnetic Waves Flashcards by Isabel Woods

Where does refraction take place?

At the bounties between layers of air at different temperatures

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What is defraction?

The spreading out of waves when they pass through a gap or around an object

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What are electromagnetic waves?

They are electric and magnetic waves disturbances that transforms energy from one place to another

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What are the hazards/problems with using UV light?

Sun burns

Skin cancer

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Why at night can you hear sound a long way away from its source?

Because sound waves refract back on the ground

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What problems do infra-red course to cells?

Skin burns

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What problems do micro and radio waves cause to cells?

Internal heating

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Why can light not be diffracted around a corner?

Because the wavelengths are to small

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How can we use information transferred?

By waves in communication

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Give examples of electromagnetic waves?

Light waves
Radio waves
Microwaves

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What is the change in direction due to (in refraction)?

A change of speed

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What type of wave are electromagnetic waves?

Transverse waves

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What is refraction?

The change in direction of waves when they travel across a boundary

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Why is violet refracted the most ?

It has a shorter wavelength

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What are gamma rays used for?

to kill censer cells
sterilise food so it doesn’t go of so quickly
to check if two metals have fitted together
to see inside your body

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Give examples of mechanical waves

Sound waves
Water waves
Waves on spring and ropes
Seismic waves (produced by earthquakes)

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How is UV light made?

Sun
Hot objects in space
Hot lights

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What can infra-red be used for ?

Remote handsets
In optical fibers
Infra-red cameras
Infra-red scanned

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What problems do UV, X-Ray and gamma rays cause to cell?

More servers cell damage

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What are pixels?

Thousands of tiny light sensitive cells

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When does the loudness of a note increase?

The amplitude of the sound waves increases

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What can we use waves for?

to transfer information

- to transfer energy

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What is the wavelength?

The distance from one crest top to another

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What are optical fibers?

They are very thin transparent fibers

They are used to transmit signals by light and infra-red radiation

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What does white light contain?

All colours of the visible spectrum

What is the amplitude?

The height of the wave crest from the position of the rest

What are microwaves used for and why?

Satellite phone and tv links They can pass through the atmosphere

Are mechanical waves transverse or longitudinal and give an example?

Both Slinky spring

What are optical fivers used for?

Medical uses

Give three facts an image in a plane (flat) mirror

It is up right Vertual The same size as the object

What is the frequency if a humans hearing range?

20-20 000 Hz

Give all the electromagnetic spectrums from longest wavelength to shortest

``` Radio Micro Infrared Visible UV X-Ray Gamma ```

What does sound travel fastest through and why?

Solids because the particles are closer together

What are the hazards/problems with using light?

Bright light can cause discomfort

What do mechanical waves need to travel through?

A medium

What happens to the air when sound waves pass through it?

It makes the air around it vibrate as it pushes and pulls it

What is the frequency and what is it measured in?

The number of wave crests paras song through a point in one second Hertz

Why do radio waves have poor reception when they go over hills?

Because they won't have diffracted enough

Can sound diffract around an open door way?

Yes

When does the pitch note increase?

When the frequency of the found waves increase

What can electromagnetic waves do?

They can travel through a vacuum at the same speed of light (300000 kilometres per second) no medium is needed

What is the visible light used for?

Vision | Photography

What is the normal?

It is a construction line perpendicular to the reflecting surface at the point of incidence

Are mobile phones safe to use?

More research needs to be done to evaluate it

What are radio waves with more than 100m used for?

National and international radio stations

What are the hazards/problems with using radio waves?

It can course: cancer, effect health, cell damage, brain damage

What are the hazards/problems with using gamma ray?

Hard to control so you could kill other cells without meaning to If exposed to it cells can mutate and cause cancer It has a short wavelength so it is very dangerouse

What are x-rays used for?

To see bones in hospitals

What are mechanical waves?

They are vibrations that travel through the medium (substance)

What is the wave equation?

Speed (m/s)=frequency (Hz) + wavelength (m)

How are microwaves made?

Many types if transmitters

How are gamma rays made?

Some radioactive substances | Given of by stars

What is the hazard with using infrared?

Over heating

The warmer it is the ............. the spread of sound

Greater

What are echoes due to?

Sounds reflected of smooth hard surfaces

What is the difference between a real image and a virtual image?

A real image can be projected onto a screen but a virtual image can only exist in a mirror

For a light ray reflected by a plain mirror what two angles are there?

Angle of reflection | Angle of incidence

Why are radio waves with different wave lengths used for different purpose ?

Because the wavelength affects how far they go, how much they spread and how much information they carry

What are hazards with using X-rays?

They cause cancer if over exposed

What are UV lights used for?

``` Sun beds Lights Bugs are attracted to the light Fake notes They can glow in the dark so they are used in discos ```

How is light/visible made?

It is emitted by luminous objects

What are radio waves with a less than 1m wavelength used for?

TV broadcasting

What can we replace with radio waves?

Bluetooth

How are x-rays made?

X-ray machines

When light passes from air into glass is the angle of refraction (inside the glass) more or less than the angle of incidence?

Less

Why can't light diffract around an open door?

Because the gap must be a similar size to the wavelength of the wave in order for diff reaction to take place

The greater the diffraction, the ............. the gap

Narrower

What are the hazard with using microwaves?

May stop working | Long exploiter can lead to brain damage

How are radio waves made?

Many transmitters Lights Stars Sparks

What happens to sound during the day time any why?

Sound refracts upwards | Because the air near the ground is warmer than the air higher up

What are radio waves used for?

Radio and tv broadcasting Radio communication Mobil phone calls

What do microwaves carried ?

Mobile phone calls

What do we mean when we say that instruments resonates?

Vibration created by a musical instrument produces sound waves