Electromagnetic Spectrum

Question 1

Electromagnetic spectrum

Answer 1

○ Changing the frequency changes the properties of the waves
○ High frequency waves are most dangerous
§ Have more energy to tear apart DNA, etc

Question 2

Electromagnetic waves

Answer 2

• A changing magnetic field will induce a changing electric field and vice-versa
• These changing fields form electromagnetic waves
• Electromagnetic waves differ from mechanical waves in that they do not require a medium to propagate
• All travel at speed of light
  § (3 x 108 m s -1
• May slow down in other media

Question 3

Radio waves

Answer 3

○ Have the longest wavelengths in the electromagnetic spectrum
○ Can be very very long or very very short
○ Don’t just play music in radio, but also carries signals for television and cellular phones

Question 4

Microwaves

Answer 4

○ Have wavelengths that can be measured in centimetres
○ Shorter, near infrared waves are not hot
§ You can’t feel them
§ Used by television remote
○ To make infrared pictures, special cameras are used
§ Red/orange areas are warmest and white/blue areas are coldest

Question 5

Visible light

Answer 5

○ Made up of various frequencies of coloured light
○ Colour is determined by the frequency of light
○ When electromagnetic radiation of this frequency falls on the retina the brain interprets it as colour

Question 6

Ultraviolent (UV) light

Answer 6

○ Has shorter wavelengths than visible light
○ Plays an important role in nature
§ Some animals have colours that change in UV light
§ Some animals can detect UV light
§ These waves are invisible to the human eye
○ Used for security coding

Question 7

X-rays

Answer 7

○ X-ray radiation has a high penetration ability and can pass right through the body
○ X-ray film forms images depending on the intensity of the x-rays falling on it
○ Shadows left by material x-rays can’t travel through (like bones or metal) form the images on medical x-rays
○ Over exposure can cause tissue damage

Question 8

Gamma rays

Answer 8

○ Have the smallest wave-lengths and the most energy of any other wave in the electromagnetic spectrum
○ Waves are generated by radioactive atoms and in nuclear explosions
○ Can kill living cells
§ Medicine uses it to its advantage to kill cancerous cells