EM spectrum

Question 1

How are radio waves made?

Answer 1

Radio waves are made by various types of transmitter, depending on the wavelength. They are also given off by stars, sparks and lightning, which is why you hear interference on your radio in a thunderstorm.

Question 2

How long are radio waves

Answer 2

1-2 km

Question 3

How high is their frequencies on the em spectrum

Answer 3

Lowest frequency

Question 4

What does VHF stand for

Answer 4

This stands for “Very High Frequency” and has wavelengths of around 2m.

Question 5

What are VHF band radio wave frequencies used for

Answer 5

This is where you find stereo “FM” radio stations, such as BBC Radio 1and Further up the VHF band are civilian aircraft and taxis

Question 6

What are UHF band radio wave frequencies used for

Answer 6

It’s used for Police radio communications, television transmissions and military aircraft radios - although military communications are now mostly digital and encrypted.

Question 7

What does UHF stand for and how long are the waves in this band of wave lengths

Answer 7

This stands for “Ultra High Frequency”, and has wavelengths of less than a metre.

Question 8

Dangers of radio waves

Answer 8

Large doses of radio waves are believed to cause cancer, leukaemia and other disorders but no proven ones

Question 9

What are the bands that radio waves are divided into

Answer 9

Long wave 1-2km
Medium wave 100m
VHF waves 2m
UHF waves less than a meter

Question 10

Medium radio waves are used for ?

Answer 10

BBC Radio 5, AM and other radios

Question 11

How do mobile phones make microwaves?

Answer 11

In a mobile phone, they’re made by a transmitter chip and an antenna, in a microwave oven they’re made by a “magnetron” . Add more.

Question 12

What uses microwaves

Answer 12

Microwaves are also used by fixed traffic speed cameras, and for radar, which is used by aircraft, ships and weather forcasters mobile phones as well as WiFi

Question 13

How do microwaves heat up food?

Answer 13

Microwaves are easily absorbed by water molecules in food, causing them to vibrate more vigorously. The microwave energy is changed to heat energy as it is absorbed, which cooks the food. Microwaves cause water and fat molecules to vibrate, which makes the substances hot.

Question 14

How do phones use microwaves

Answer 14

Mobile phones use microwaves, as they can be generated by a small antenna, which means that the phone doesn’t need to be very big. The drawback is that, being small, mobiles phones can’t put out much power, and they also need a line of sight to the transmitter

Question 15

How is most microwave radar used

Answer 15

The most common type of radar works by sending out bursts of microwaves, detecting the “echoes” coming back from the objects they hit, and using the time it takes for the echoes to come back to work out how far away the object is.

Question 16

How long is a microwave wavelength

Answer 16

Their wavelength is usually a couple of centimetres. Stars also give off microwaves.

Question 17

What are the dangers of microwaves

Answer 17

Dangers
Prolonged exposure to significant levels of microwaves is known to cause “cataracts” in your eyes, which is a clouding of the lens preventing you from seeing clearly. small doses of microwaves from mobile phones might affect parts of your brain - after all, you’re holding the transmitter right by your head. Other research is inconclusive, although there is a feeling that you’re more vulnerable if you’re young and your brain is still growing.

Question 18

Where are infrared waves on the em spectrum

Answer 18

Just before visible hence why infra means before.

Question 19

What is the order of the waves on the em spectrum

Answer 19

Radio waves
Microwaves
Infra red waves
Visible light
Ultra violet waves
X rays
Gamma rays

Question 20

What are infra red waves used for?

Answer 20

remote controls for TVs and video recorders, and physiotherapists use heat lamps to help heal sports injuries. IR is also used for short-range communications, for example between mobile phones, or for the Dolby Screentalk headset system used in some cinemas.

Because every object gives off IR waves, we can use them to “see in the dark”. Night sights for weapons sometimes use a sensitive IR detector Passive Infra-Red” (PIR) detectors are used in burglar alarm systems, and to control the security lighting that many people have fitted outside their houses.

These detect the Infra-Red emitted by people and animals. There is also thermal imaging used by rescue people to see people in the dark at night or fire people through smoke in a fir see a body.

Question 21

How do we make infra red waves

Answer 21

You probably think of Infra-red waves as heat, because they’re given off by hot objects, and you can feel them as warmth on your skin.
Infra Red waves are also given off by stars, lamps, flames and anything else that’s warm - including you

Question 22

Dangers of infrared waves…

Answer 22

The danger to people from too much Infra-Red radiation is very simple - overheating

Question 23

Wave length of infrared waves

Answer 23

between 780 nm and 1 mm

Question 24

Dangers of visible light

Answer 24

Too much light can damage the retina in your eye

Question 25

What is a condition of something to give offf visible light

Answer 25

Hot enough to glow.

Question 26

Uses of UV light

Answer 26

Uses for UV light include getting a sun tan, detecting forged bank notes in shops, and hardening some types of dental filling. Ultraviolet rays can be used to kill microbes.

Question 27

Why does ultra violet light make things fluoresce

Answer 27

This happens because substances in washing powder "fluoresce" when UV light strikes them - they absorb the UV and then re-radiate the energy at a longer wavelength. Your teeth do the same thing! The lamps are sometimes called "blacklights" because we can't see the UV coming from them.

Question 28

What are dangers of UV light

Answer 28

Large doses of UV cause sunburn and even skin cancer. Large doses of UV can damage the retina in your eyes

Question 29

Are x rays high or low energy, frequency and why are they used a lot by people.

Answer 29

X-rays are very high frequency waves, and carry a lot of energy. They will pass through most substances, and this makes them useful in medicine and industry to see inside things.

Question 30

What gives off x rays

Answer 30

X-rays are given off by stars, and strongly by some types of nebula

Question 31

How do x ray machines work

Answer 31

An X-ray machine works by firing a beam of electrons at a "target". If we fire the electrons with enough energy, X-rays will be produced. Also The machines are managed by a trained x-ray technician. They pass easily through soft tissues, but not so easily through bones. X-ray picture of human brainWe send a beam of X-Rays through the patient and onto a piece of film, which goes dark where X-Rays hit it. This leaves white patches on the film where the bones were in the way. Sometimes a doctor will give a patient a "Barium Meal", which is a drink

Question 32

What are x rays used for

Answer 32

Medicine x rays X-Rays are also used in airport security checks, to see inside your luggage. They are also used by astronomers - many objects in the universe emit X-rays, which we can detect using suitable radio telescopes. Lower energy X-Rays don't pass through tissues as easily, and can be used to scan soft areas such as the brain.