Electromagnetic Waves

Electromagnetic Waves Electromagnetic waves are transverse waves that can transfer energy without a medium. Electromagnetic waves occur when electric and magnetic fields vibrate at right angles to each other.

Electromagnetic Radiation These waves transfer energy called electromagnetic radiation. This is how light from the sun and stars travel through space to Earth. Light travels 300,000 kilometers per second. Light from the sun travels 150 million kilometers to Earth in 8 minutes! All electromagnetic waves travel at the same speed.

Electromagnetic Spectrum All electromagnetic waves travel at the same speed, but they have different wavelengths and different frequencies. Waves with the longest wavelengths have the lowest frequencies. Waves with the shortest wavelengths have the highest frequencies. The higher the frequency, the higher its energy.

The electromagnetic spectrum shows the different electromagnetic waves in order of increasing frequency and decreasing wavelength.

Radio Waves Have the longest wavelengths and lowest frequencies Most of the radio waves we receive travel through air, antennas pick up the radio waves and send them through wires to your radio. Each radio station is assigned a particular radio frequency for their broadcast- this specific frequency is called the carrier wave. Carrier waves can transmit a signal in one of two ways: AM radio broadcasts info by varying the amplitude of the carrier wave. FM radio varies the frequency of carrier wave

Microwaves Types of radio waves with the shortest wavelengths and highest frequencies The electromagnetic waves in a microwave oven bounce around inside the oven causing food to get hot. Microwaves can pass right through glass and plastic so they do not heat glass and plastic containers (the food transfers heat to the containers) Objects like metal, reflect microwaves.

Infrared Infrared waves have shorter wavelengths and higher frequencies than radio waves Infrared waves is the energy you feel as heat (often called heat rays) Objects that use infrared waves include heat lamps, toasters, electric stove, & infrared cameras.

Visible Light Visible light has shorter wavelengths and higher frequencies than infrared. The longest wavelengths of visible light are red, the shortest are violet. Each different wavelength of light has a different color.

Ultraviolet Ultraviolet rays have wavelengths that are just shorter than visible light (means “beyond violet”) The energy in ultraviolet rays is great enough to damage and kill living cells. Hospitals use ultraviolet lamps to kill bacteria and treat jaundice in newborn babies. Small doses are beneficial to humans, they produce vitamin D. Too much exposure can cause skin cancer and damage your eyes.

X-Rays X-rays have very short wavelengths and higher frequencies than UV rays. They carry more energy than UV rays and can penetrate most matter (except bone or lead). Too much exposure to X-rays can cause cancer.

Gamma Rays Gamma rays have the shortest wavelengths and highest frequencies in the electromagnetic spectrum Some radioactive substances and certain nuclear reactions produce gamma rays. Some objects in space also give off gamma rays (ex. dying stars) Gamma rays have the greatest amount of energy and great penetrating ability. They can cause serious illnesses, however they have some medical uses to kill cancer cells through radiation therapy.

Summary: EMS: https://youtu.be/cfXzwh3KadE Infrared: https://youtu.be/1Un08ziq82Y