# Physics - EM Spectrum

• Created by: I.T.P
• Created on: 28-01-18 12:07

## Physics - EM Spectrum and Waves

Frequency is measured in Hertz ( Hz ).

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## Physics - EM Spectrum and Waves

Refraction is when waves pass into the new material but changes the direction it's travelling.

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## Physics - EM Spectrum and Waves

You can describe waves as being transverse or longitudinal.

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## Physics - EM Spectrum and Waves

All electromagnetic waves are transverse.

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## Physics - EM Spectrum and Waves

Reflection is when the waves bounce off a material.

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## Physics - EM Spectrum and Waves

Amplitude is the height of a wave.

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## Physics - EM Spectrum and Waves

The symbol for wavelength is Lambda.

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## Physics - EM Spectrum and Waves

Two examples of transverse waves are ripples on water and waves on string.

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## Physics - EM Spectrum and Waves

When light waves hit a black object they're absorbed and turned into heat.

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## Physics - EM Spectrum and Waves

A wavelength is the length of one complete wave. This can be from the top of one wave to the same point of the next or the bottom or side of a wave to the same point on the next wave. It is measured in meters and has the symbol lambda.

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## Physics - EM Spectrum and Waves

All objects are continually emitting and absorbing EM radiation over a range of wavelengths.

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## Physics - EM Spectrum and Waves

The speed of light is 3x10 (to the power of 8) m/s.

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## Physics - EM Spectrum and Waves

A transverse wave is a moving wave that consists of oscillations occuring 90 degrees to the direction of energy transfer.

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## Physics - EM Spectrum and Waves

The frequency of a wave is counted as the number of waves that pass a point per second.

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## Physics - EM Spectrum and Waves

Transmitting is when a wave is transmitted, the wave passes through the material and is not absorbed or reflected.

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## Physics - EM Spectrum and Waves

Waves transfer energy and information.

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## Physics - EM Spectrum and Waves

In longitudinal waves, the vibrations are along the same direction as the direction of travel.

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## Physics - EM Spectrum and Waves

Wavelengths are measured in meters.

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## Physics - EM Spectrum and Waves

The units for wavespeed are meters per second (m/s).

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## Physics - EM Spectrum and Waves

The velocity of a wave can be calculated from its wavelength and its frequency.

velocity = frequency x wavelength

v = f x lambda

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## Physics - EM Spectrum and Waves

The intensity of the different wavelengths depends on the objects temperature. As the temperature of an object increases, the intensity of every emitted wavelength increases - hot objects shine more brightly!

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## Physics - EM Spectrum and Waves

Oscillating electric currents produce an oscillating electromagnetic field. Some of these fields take the form of an electromagnetic wave (which itself oscillates). When a radio wave reaches an antenna the oscillating electric current in the antenna which can then be amplified and decoded.

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## Physics - EM Spectrum and Waves

Different substances may absorb, transmit, refract, or reflect electromagnetic waves in ways that vary with wavelength. E.g. solar radiation.

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## Physics - EM Spectrum and Waves

2. Microwaves

3. Infared

4. Visible light

5. Ultraviolet

6. Xray

7. Gamma rays

This is the order of the EM spectrum. 1 being not dangerous and 7 being very dangerous!

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## Physics - EM Spectrum and Waves

Radiation can cause changes in atoms. Some parts of the electromagnetic spectrum can cause atoms to become ions. Changes in the nuclei of atoms can produce gamma radiation. When materials are heated, they can produce visible light or infared radiation.

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