§1 Electromagnetic radiation

• Natuurkunde
• Middelbare school
• vwo
• Leerjaar 3

Radiation

Learning objectives

• You can describe how a transmitter and a recipient use electromagnetic waves to transport information. 
• You can describe three features of electromagnetic radiation.
• You can do calculations using the wavelenght, speed of light and frequency. 
• You can classify the different types of electromagnetic radiation within the elctromagnetic spectrum. 
• You can describe the effects of ionising and non-ionising radiation.

Radiation around us. 

Throughout the universe, objects emit radiation

Radiation is a form of light that is not always visible!

• Visible light
• radio waves
• Gamma radiation
• Infrared (IR) radiation 
• Wi-Fi
• UV radiation

Elektromagnetic spectrum

Radiation occurs in different ways; the so-called "spectrum". The stronger the radiation, the smaller its wavelength.

Ionising radiation

• Radiation that can destroy molecules.
• Radio waves, IR radiation and visible light aren't ionising. 
• X-rays and gamma-rays are highly ionising. Extremely small quantities can cause health damage. 

Elektromagnetic waves

• 3D
• Electromagnetic waves propagate indipendently - even through a vacuum. 
•  Electromagnetic waves always have the same speed : 3,0*10^8 m/s. This is the speed of light and it  carries symbol c.

Frequency and wavelenght

The number of waves that pass 

in 1 second, is called the 

frequency (Hz).  

The distance between 2 

successive wave peaks is 

called Wavelength.

• Lambda        = wavelengthe in metres (m)
• c = speed of light in metres per second (m/s)
• f = frequency in hertz (Hz)

λ=​f​​c​​

λ

A laser radiates blue light with a wavelength of 470 nm.
Calculate the frequency of this blue light.

λ=​f​​c​​

Elektromagnetic waves

Transmit and Receive 

Radiation can be used to send and receive wireless signals.

The transmitter

The moving electrons generate an electromagnetic field, which emits radiation at a certain frequency f.

The Recipient

Electrons in the antenna of the receiver start to vibrate at frequency f, under the influence of the radiation. The signal has now been transmitted

On 6 august 2012, the mars rover Curiosity landed on the planet. The signal from Curiosity only reached Earth after 13 minutes and 48 seconds.

Calculate the distance between Mars and the Eart at that moment. Give the answer in millions of kilometers.

c = 3,0*10^8 m/s

1 million = 1.000.000

CH 6 § 1 - 2,3,6,9,10