What are electromagnetic waves?

Electromagnetic waves are waves that have both electric and magnetic fields.

They do not have to have a medium to travel through.

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The Electromagnetic Spectrum

All the different types of electromagnetic waves put in order from lowest energy to highest energy.

All these types of waves travel at the same speed, but they have different wavelengths and frequencies.

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Radio waves

Longest Wavelength and lowest energy Many uses

– Radios– AM = amplitude modulation. 1070 AM means the waves

have an amplitude of 1070– FM = frequency modulation. 93.1 FM means the waves

have a frequency of 93.1– TV– RADAR– MRI (Magnetic Resonance Imaging)

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Microwaves

Sometimes considered a type of radio wave. Most commonly used in a microwave oven. The energy from the microwaves make the water

molecules start to move. The more the water moves, the more thermal energy = hotter the food.

Waves pass through glass and plastic. Metal reflects microwaves. Microwaves also are used to transmit cell phone

calls

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Infrared waves

Can not see infrared waves. Felt as heat. Thermograms are pictures that show hot

areas as red and cool areas as blue.

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Visible Light

The smallest part of the EMS.

Most Electromagnetic waves we CAN NOT see.

Red has the longest wavelength.

Violet has the shortest wavelength.

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Ultraviolet

These waves have more energy than visible light and are dangerous.

There is enough energy in UV waves to kill living cells. Hospitals use UV light to kill bacteria on equipment.

Too much UV causes humans to get skin cancer. The UV actually changes your DNA until it is the DNA of a cancer cell.

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Small amounts of UV can be helpful to people. UV causes your body to make vitamin D, which you need for strong bones and teeth.

UV also treats jaundice

in babies.

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Ultraviolet light is invisible to humans, many insects can see it.

Bees see colors differently than we do. They can see Ultraviolet light and some of what we see. This makes the parts of flowers that contain the nectar a color that stands out to the bee.

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X-Rays

X-Rays carry even more energy than UV.

They can go through most materials but not bone and lead.

Too much exposure to X-Rays cause cancer.

Can be used in industry to see if the steel structure of a building is safe after an earthquake.

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Gamma

The type of wave with the most energy, therefore the most dangerous.

Are so strong they can kill living cells. Gamma waves are radioactive. They are given off

by nuclear power plants and weapons. Are used in radiation therapy to kill cancer cells. Food that is being shipped a far distance is irradiated

with gamma rays. This kills the organisms that could make the food decay or make people sick.

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