ElectroMagnetic Spectrum Section 9.1

Electromagnetic spectrum Different types of electromagnetic waves make up the electromagnetic spectrum. The electromagnetic spectrum is continuous. It is a range of EM waves with different wavelengths and frequencies.

Electromagnetic spectrum Different types of electromagnetic waves oscillate at different rates. (Oscillate means to move back and forth at a regular speed) The rate determines the frequency and wavelength of each type of EM wave. The faster the wave oscillates, the higher the frequency and the shorter the wavelength.

As wavelength of an EM wave increases, the frequency of the EM wave decreases. As frequency of an EM wave increases, the energy carried by EM wave increases. This means that waves with SHORTER wavelengths, have HIGHER frequencies, and so MORE energy.

LIGHT Light is ENERGY carried by ELECTROMAGNETIC WAVES, also known as EM RADIATION, the greater the energy the wave has, the higher the frequency. We classify the different types of light by WAVELENGTH, visible light (what we see as colors) for example have wavelengths between 700 nanometers and 380 nanometers (different colors have different wavelengths). INTENSITY: a measure of the brightness of light, depends on the AMPLITUDE, the higher the amplitude the more intense. (Like playing a musical note on an electric piano and raising/lowering the volume, the note stays the same but the intensity of the sound changes) NOTHING moves faster than light, it travels at 300,000,000 meters per second in air, but it slows down a little in liquids and a little more in solids.

REVIEW QUESTIONS What is light? What determines the type of light carried by an EM wave? What determines the intensity of light carried by EM waves? What happens to the energy and wavelength of light as the frequency increases? Compare how fast light goes in a gas, liquid, and solid, and vacuum (space)

Sound vs light LIGHT - Light waves are electromagnetic waves BOTH - Light waves are transverse waves - Travel fastest in a vacuum - Can travel through a vacuum - Energy is determined by the frequency of the light wave SOUND Sound waves are mechanical waves - Sound waves are longitudinal waves - Travel fastest in a solid - Produce noise you can hear - Cannot travel through a vacuum - Energy is related to amplitude BOTH - Waves - Carry energy - Can travel through a solid, liquid or gas

Review Questions Sound waves are ________ waves and light waves are __________ Waves. What type of waves travel through a vacuum? A. Light waves B. Sound waves C. Both True/False: Light waves travel much faster than sound waves. The speed of light and sound waves change when they travel through vacuum, gasses, solids, or liquids. Describe how the speed of sound changes through different states of matter vs. the speed of light.

Electromagnetic spectrum We classify different types of electromagnetic waves by wavelength or frequency. There are 8 major types of electromagnetic waves: Long radio waves Radio waves Microwaves Infrared Visible light Ultraviolet X-rays Gamma Rays

Long Radio Waves Wavelengths greater than 1,000 meters They are the Longest waves Long radio waves have the lowest frequency USED FOR: Aeronautical & marine navigation used to transmit Morse Code

Radio waves Their wavelength is between 1 meter and 1,000 meters These waves have the SECOND LONGEST wavelength, and the SECOND LOWEST frequency USED FOR: Radio & TV broadcasting, radar, lightning & stars

Mircrowaves Wavelength is between 1millimeter (mm) and 1 meter (THIRD LONGEST) Frequency is THIRD LOWEST USED FOR: WIFI Cellphones GPS Air traffic Control Weather Forecasting Cooking (your microwave)

Infrared Wavelength is between 700 nanometers (nm) to 1 millimeter (mm) (nanometers are 1,000,000 times smaller than millimeters, so the wavelengths can be very small but is still the FOURTH LONGEST) Frequency is FOURTH LOWEST USED FOR: Infrared is normally associated with Thermal Energy (HEAT)

Visible light THIS IS THE PART OF THE SPECTRUM WE CAN ACTUALLY SEE (THE ONLY PART WE CAN SEE) We see visible light as colors Its wavelength can range from 380 nanometers (the color RED) to 700 nanometers (the color VIOLET) Its frequency can be from 4.3∗ 10 15 Hz to 7.9∗ 10 15 Hz USES FOR: Made of 7 colors RED HAS THE LONGEST WAVELENGTH VIOLET HAS THE SHORTEST WAVELENGTH VERY SMALL PART OF THE ELECTROMAGNETIC SPECTUM

VISIBLE LIGHT (COLORS) Remember ROY G BIV RED longest wavelength (Lowest Frequency) ORANGE YELLOW GREEN BLUE INDIGO VIOLET Shortest Wavelength (Highest Frequency)

ultraviolet Wavelength can vary from 380 nanometers to 10 nanometers (SIXTH LONGEST or THIRD SHORTEST) Frequency is SIXTH LOWEST or THIRD HIGHEST USED FOR: Helps produce Vitamin D in our skin (causes sun tans) TOO MUCH can cause sun burns OUCH! Can also damage eyes (THAT’S WHY WE WEAR SUNGLASSES)

X-rays Wavelength can be from 10 nanometers to as low as .01 nanometers (SEVENTH LONGEST or SECOND SHORTEST) Frequency is SEVENTH LOWEST or SECOND HIGHEST USED FOR: Medical imaging (like when you break your arm) Airport Security (like the machine they use to check your luggage) Can be damaging to cells

Gamma rays Wavelength is less than .01 nanometers (SHORTEST WAVELENGTH!!!!!) How high is this frequency compared to the others if the wavelength is the SHORTEST? MOST DANGEROUS TYPE OF WAVES!!!!!! USED FOR: Radioactive Decay Cause radiation poisoning Extremely dangerous

As A review let’s watch this video https://www.youtube.com/watch?v=m4t7gTmBK3g

Review Questions 1. Electromagnetic waves with a high frequency have a: a. long wavelength b. short wavelength c. faster velocity d. slower velocity 2. What type of electromagnetic wave has the longest wavelength? a. Long radio waves b. Radio waves c. Microwaves d. Gamma rays

Review Questions 3. What type of electromagnetic wave is associated with thermal energy? a. Microwaves b. Infrared c. Visible light d. Ultraviolet light 4. What is the relationship between an electromagnetic wave’s frequency and the energy carried by the wave? _____________________________________________________________