Electromagnetic Spectrum
What is a wave? A disturbance involving the transfer of energy from place to place
What types of waves are there? Transverse Waves Longitudinal waves
What are wavelength and frequency? Wavelength- the distance between two corresponding parts in a wave. (Example crest to crest) Frequency- the number of waves that pass a given point in a certain amount of time.
What travels in waves? Water Sound Electromagnetic energy
What is electromagnetic radiation? Energy! Vibrating electric fields Vibrating magnetic fields
What does electromagnetic energy come from? Everything that has energy!
What can electromagnetic waves travel through? Air/gases Water/liquids Solids
Can these waves travel through anything else? They don’t need a medium at all! Can travel through empty space! Why is this a good thing?
How fast does electromagnetic radiation travel? The speed of light! 300,000km/second It only takes light 8 minutes and 20 seconds to travel all the way from the sun to the earth (150,000,000 miles!)
Are there different types of electromagnetic waves? Do all electromagnetic waves travel at the same speed? List different types of waves you have heard of on page ________ in your interactive science notebook.
The electromagnetic spectrum Radio waves Microwaves Infrared rays Visible light Ultraviolet rays X-rays Gamma rays
The electromagnetic spectrum
Another look
How different are the wavelengths?
Radio waves Longest wavelengths Radios and TV’s depend on these
Microwaves Shorter wavelengths and higher frequencies than radio waves. Microwave ovens Radar Cell phones
Are microwaves good for you?
Infrared Rays Wavelengths shorter than microwaves Higher frequencies, more energy “Heat rays” Thermogram
Visible Light The color we perceive depends on the wavelength of light. Red is longer wavelength, lower energy Blue is shorter wavelength, higher energy
But wait… light all appears white to me!
Ultraviolet Rays Higher frequency than visible light Carry more energy Can damage or kill living cells (example sunburn)
How does UV Radiation harm us?
Be careful in the sun!
X-Rays Wavelength shorter than x-rays High energy Can go through all but most dense matter What do we use x-rays for?
Gamma Rays Shortest wavelengths Highest frequencies Medical uses – can see inside the body Telescopes