EQ: What is the electromagnetic spectrum?

• Electromagnetic Spectrum
– Range of electromagnetic waves when they are ordered by increasing frequency
– Remember all EMW travel at the same speed, but they have different wavelengths and frequencies
• As the wavelength decreases, the frequency increases
• The amount of energy carried by EMW increases as its frequency increases.

• Made up of 7 different types of waves

Radio Waves - EMW with longest wavelengths and lowest frequencies
Can travel through a vacuum but most of our radio waves travel through air.
1. Antennas pick up radio waves from the air.
2. Then the radio waves go to the wires in your radio
3. The radio converts the EMW into sound that comes out your radio

Microwaves – shortest wavelengths and highest frequency of radio waves
Microwave Ovens most common use
– Microwave gives off EMW that bounce around the inside of the oven and penetrate the food
– Water molecules in the food absorb the energy from the waves, causing the food to get hot
– Can pass through plastic and glass, not metal
Microwaves also used for cellular telelphone calls

• Stands for radio detection and ranging
• Used to locate objects
• Use radio waves and the Doppler effect to calculate speed of vehicles

• Radio waves used in medicine to produce pictures of tissue in the human body

Give off heat – heat lamp, electric stove, toaster. Humans can sense it
Have shorter wavelengths and higher frequencies than radio waves
Infra means below – below red on the color spectrum
Thermogram – pictures taken by infrared camera. Shows regions with different temperatures with different colors
– Used to detect motion of clouds, growth of plants

• The light we can see
• Longest wavelength of visible light are red, shortest is purple
• Rainbow or prism refracts, or bends the light waves to produce different colors

• Waves

• UV rays
• Ultra is Latin for beyond, so these waves are just beyond the color violet
• Carry more energy than visible light because they travel at a higher frequency
• UV lamps used to kill bacteria
• UV waves help produce vitamin D in the body, cause sunburn

• Carry more energy than UV rays because of their higher frequency
• Can penetrate most matter with the exception of bone and lead. These are too dense

• Shortest wavelength and highest frequency
• Used in radiation therapy to kill cancer cells
• Examine body’s internal structure
Supernova

• Fill In
– What did I learn
– Confused
– Say
– Read pages 79– 86, questions 1-6 and page
87 “Are cell phones harmful?”