WELCOME! Our Sun is the major source of energy for our planet. Consider all you know about the Sun and it’s energy and answer these questions: 1. What form(s) of energy do we receive from the Sun? 2. How does the Sun’s energy arrive on Earth? 3. List 3 ways the Sun’s energy is used by the Earth and its inhabitants.

TODAY’S GOALS  Summarize the properties of electromagnetic waves  Explain how electromagnetic waves are alike and different  Describe the waves that make up the electromagnetic spectrum.

WHAT IS AN ELECTROMAGNETIC WAVE?  Book definition: a disturbance that involves the transfer of electric and magnetic energy.  Another definition: vibrating magnetic fields that move at the speed of light through space or other medium. A.K.A. EM Waves

SO, WHERE DOES THE ENERGY COME FROM?  Electromagnetic Radiation: the energy that electromagnetic waves transfer through matter or space  The Sun’s energy arrives to Earth in the form of electromagnetic radiation

COMPARING EM WAVES  Wavelength: the distance between the crest of one wave to the crest of the next

COMPARING EM WAVES  Frequency: the number of waves that pass a given point in a certain amount of time. The higher the frequency, the higher the energy!

HOW FAST DO EM WAVES TRAVEL? A. The speed of sound B. The speed of light C. The speed of a jet D. It depends on the type of EM wave All EM waves travel at the same speed in a vacuum (like space). They all travel at the speed of light, which is approximately 300,000 km per second.

THE COLOR RED HAS THE LONGEST WAVELENGTHS OF ALL COLORS. IDENTIFY WHICH WAVE REPRESENTS RED. A. i B. ii C. iii The wavelength is the distance between two crests within a wave. The farther apart they are, the longer the wavelength.

AS THE FREQUENCY OF A WAVE INCREASES, THIS ALSO INCREASES: A. The speed of the wave B. The wavelength C. The amount of energy D. The electromagnetic radiation Frequency is the number of waves in a given amount of time. When frequency increases, the energy of the wave increases.

TABLE DISCUSSION  How are wavelength and frequency related?  Explain in your own words WHY this occurs.  Write your group’s conclusions on your whiteboard

GOAL CHECKUP  Summarize the properties of electromagnetic waves  Now we know:  EM waves are made up of electric and magnetic fields that travel through space and matter at the speed of light  All waves travel at the same speed, but they have different wavelengths and frequencies You don’t need to copy this page

GOAL CHECKUP (CONTINUED)  Now we also know:  The wavelength is the distance between two crests within a wave  The frequency is the number of waves that occur in a given amount of time. The greater the frequency, the greater the amount of energy.  Long wavelength = lower frequency  Short wavelength = high frequency You don’t need to copy this page