Electromagnetic Radiation and Light 7th Grade Science LaVilla School of the Arts

By the end of this lesson, you should be able to… Identify, compare and contrast the types of EM radiation from the Sun Know common uses and applications of the EM spectrum Know the order of frequencies and wavelengths in the EM spectrum Interpret the relationship between frequency and wavelength in the EM spectrum Describe and give examples of light reflection, refraction and absorption Know that wavelength is related to the amount of energy carried.

Lets recap what EM waves are… They do NOT need a medium to travel They only travel through transverse waves The Sun is a major source of EM waves

What is radiation? Radiation is the transfer of energy as EM waves. EM waves can have a variety of different frequencies and wavelengths. There are 7 sources of EM waves that are part of the EM spectrum:

ULTRAVIOLET LIGHT (UV) What is the EM spectrum? There are 7 sources of EM waves that are part of the EM spectrum: RADIO WAVES MICROWAVES INFRARED LIGHT VISIBLE LIGHT ULTRAVIOLET LIGHT (UV) GAMMA RAYS

Types of EM radiation MAKE A 2 COLUMN CHART LIKE THIS: TYPE OF EM RADIATION USES RADIOWAVES MICROWAVES INFRARED LIGHT VISIBLE LIGHT UV LIGHT X-RAYS GAMMA RAYS

Types of EM radiation ANSWER KEY: TYPE OF EM RADIATION USES RADIOWAVES Radio and TV MICROWAVES Cooking, radar, TV, other INFRARED LIGHT HEAT from sun, fires, radiators VISIBLE LIGHT Things can be seen UV LIGHT Absorbed by skin, florescent tubes X-RAYS See inside of bodies GAMMA RAYS Medical treatment (kills cells)

What about the SUN? The Sun gives off mostly visible light, but gives off radiation in ALL areas of the EM spectrum!

How much is too much radiation? Answer…. The frequency or the wave. The HIGHER the frequency, the MORE ENERGY that wave has = more dangerous. Like UV rays and gamma rays Gamma rays kill cancer cells The LOWER is frequency, the LESS ENERGY that wave has = less dangerous. like radio waves, microwave, infrared, visible light

ROYGBIV…. What is it? Red Orange Yellow Green Blue Indigo Violet

The longest wavelength = RED The shortest wavelength = VIOLET What determines the color of light? FREQUENCY! The longest wavelength = RED The shortest wavelength = VIOLET

How do we see white or black? When we see WHITE… ALL colors of ROYGBIV are reflected When we see BLACK… ALL colors of ROYBGIV are absorbed