The Nature of Electromagnetic Waves

Objectives Compare the types of electromagnetic radiation in terms of wavelength, frequency, energy and application. Explain how seeing in different types of light is helpful in astronomy.

Electromagnetic waves- transverse waves with some electrical & magnetic properties.

Electromagnetic radiation- energy transferred by electromagnetic waves. ***can travel in a vacuum

Electromagnetic spectrum- range of electromagnetic waves in order of increasing frequency.

Electromagnetic Spectrum Animation /waves_particles/index.html /waves_particles/index.html

All electromagnetic waves travel at the same speed. 300,000 km/sec or 186,000 miles/sec.

Radio Waves *Longest wavelength, shortest frequency *Picked up by antennas *Each radio station broadcasts at a different frequency

Microwaves *Radio wave with the shortest wavelength & highest frequency. *Used in microwave ovens *Used to transmit cellular phone calls

Radar *Short-wavelength microwaves *Monitor speed of vehicles *Track weather systems

Infrared Waves *Can feel them as warmth *Used in heat lamps *Warmer objects give off more infrared rays *Thermograms shows regions of different temperatures in colors *Use infrared cameras or binoculars in the dark ac.caltech.edu/ima ge_galleries/ir_zoo/

Visible Light *Roy G. Biv

Ultraviolet Rays *energy is great enough to kill living cells *small doses are beneficial, they stimulate cells to produce vitamin D and can be used to treat jaundice in newborns.

X-Rays Cannot penetrate bone or lead Too much exposure can cause cancer.

Gamma Rays shortest wavelength, highest frequency produced by some radioactive substances & nuclear reactions can cause illness used in radiation therapy for cancer used to examine the body’s interior (Nuclear Medicine)

Space Images in Different Wavelengths c_classroom/multiwavelength_astronomy/ multiwavelength_museum/ c_classroom/multiwavelength_astronomy/ multiwavelength_museum/

Objective Check Compare radio waves and x-rays in terms of wavelength, frequency, energy and application. Give an example of how seeing in a different type of light is helpful in astronomy.