1. Electromagnetic Spectrum

2. Electromagnetic Spectrum
Transverse waves
Do not need a medium to move through.
Medium: a material through which waves travel.

4. Visible Light The only part of the spectrum that we can see.
Every light source is made up of a different combination of colors.

5. Spectroscopes
An instrument used to observe the spectra of light sources.

6. Spectroscopes
Use your spectroscope to look at the following light sources:
Classroom Lights
Incandescent bulbs at lab stations
Record the different colors you see.

7. Why does light look white?
When you mix all colors of light together, the light appears white.

8. Why do we see different colors?
Objects absorb some colors and reflect others.

9. Radio Waves Have long wavelengths & low frequencies.
Microwaves use radio waves.

10. Infrared Radiation Wavelength is slightly longer than visible light.
Example: we are warm, because we are absorbing infrared radiation from the sun.

11. Ultraviolet Light Has a higher frequency.
Can be healthy: Vitamin D, Hospitals use to kill bacteria & viruses to sterilize.
Overexposure can be harmful: kills healthy cells, leading to skin cancer.
We are protected by the ozone layer.

12. X Rays & Gamma Rays X Rays: Very short wavelength.
Have higher energy and greater penetrating power.
Gamma Rays have highest frequency.
Are emitted from nucluei of radioactive atoms.
Example: Chemo Therapy