7-1 EM spectrum

• Natuurkunde
• Middelbare school
• vwo
• Leerjaar 3

Uv, IR and other radiation 

Bluetooth 

- On

- VPN off

Stationary

- Books

- Pen and pencil

- iPad

Report

- NO

Lessonup

- Yes

Bags in

the cuboard

Phones in the phone holder

The electromagnetic spectrum

There is also solar radiation which you can not see, but you can detect it in other ways.

Uv radiation

• Drinking water supply companies use UV radiation to kill bacteria in the water. 
• Bees can see UV radiation.
• A large portion of the UV 

        radiation is blocked by the 

       ozone layer, clouds and 

       dust particles

0

Which type of radiation is used by bees to better see the stammens of flowers?

1. IR
2. UV
3. Gamma
4. x-ray

Next to which colour do we find UV radiation?

1. Red
2. Violet
3. Radio
4. IR

Which of the following is a use of UV radiation?

1. night vision weapons
2. Remote control of a television
3. Photo's to observe broken bones
4. Killing bacteria

Infrared radiation

Also called thermal radiation.

Examples: 

• A coal fire, 
  
• Sunlight, 
  
• Remote controll of a TV, 
  
• Rattlesnakes have grooves in their heads that are sensititve    to infrared radiation. They use it to spot prey at night.

0

What type of radiation does a rattlesnake use to spot it's prey at night?

1. UV
2. Gamma
3. IR
4. Micro

DANGER...

• Not all radiation is harmful.
  
• Only x-rays and gamma rays are dangerous. 
  
• X-rays can move through the soft tissue in our bodies, but not through the bones. 
  
• Gamma rays can move through just about everything, except through thick concrete and flat lead. 
  
• Damaged cells can turn into cancerous cells. 

Micro- and radio- waves

Mobile phones, mobile internet, bluetooth, radio and television are all examples of microwaves and radio waves. 

The body does not notice these forms of radiation. An exception is the microradiation from a microwave oven. This is so intense that it heats food. 

Why is there more UV radiation high in the mountains?

1. It is closer to the sun
2. There is less atmosphere
3. There is a higher oxygen level
4. Mountains reflect UV radiation

Fluorescence

• Ink that gives off light when it is radiated by a UV lamp. 
  
• Fluorescent substances are often added to washingpowder and toothpaste to make clothes or teeth look whiter. 
  

Velocity

• All forms of electromagnetic radiation travels with a velocity of 300 000 km/s.
  
• This is 7 times around the 

        world in 1 second. 

• Nothing is faster than this.
  

Uv, IR and other radiation 

0

Frequency and wavelength

Frequency is the number of times that a source moves up and down (number of waves per second) 

f (Hz)

Wavelength is the distance between two consecutive crests (or troughs)

     (m)

λ

Golflengte en frequentie

λ=​f​​c​​

Photo of your answer to questions 12

Homework

Not try questions 1 up to and including 6 from the digital method and the test yourself chapter 1