ELECTROMAGNETIC RADIATION

Haitham Alahmad

ELECTROMAGNETIC RADIATION

-Electromagnetic radiation is one of the many types of energy and may appear in the form of visible light, x-ray, infrared radiation or radio wave.

-The SI unit of radiation is electron volte(eV)

- Electromagnetic radiation vary in energy, frequency, and wave length:

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Electromagnetic radiation vary in energy, frequency, and wave length

Electromagnetic radiation vary in energy, frequency, and wave length

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Characteristics of electromagnetic radiation

-Electromagnetic radiation consists of vibrations in electric and magnetic fields, These vibrations:-

- Have no charge

- No mass

- Travel at the speed of light.

- Moves in sinusoidal waves.

- Electromagnetic radiation is described in terms of Velocity (c), Frequency (ƒ), Period (T), Wavelength (λ) and Amplitude

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Velocity (c)

-All electromagnetic radiation in vacuum travels at 3*108 meter per second.

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Frequency (ƒ)

-The frequency (ƒ) of a wave is the number of cycles per second (T).

ƒ = 1/T

The unit of frequency is the hertz (Hz) which equal one cycle per second.

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Period (T):

-It is the time required for one complete cycle.

- A wave with a frequency of 2 cycles per second has a period of 1/2 second

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Wavelength (λ)

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- It is the distance between adjacent peaks of a waves.

- Electromagnetic radiation with shorter wavelengths will have higher energy and frequencies and greater penetration.

- Wavelength is measured in meters, centimeters or millimeters.

Wavelength (λ)

• Electromagnetic wave velocity, frequency, and wavelength are related by:-

C = ƒ λ

C = the speed of light.

ƒ = the frequency.

λ = lambda is the wavelength.

Frequency and wavelength are inversely proportional

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Wavelength (λ)

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Amplitude

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-The amplitude of a wave is the maximum height, or difference from zero (in either direction) of the peaks.

Quantum theory

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- Electromagnetic radiation can act as a wave or a particle. When electromagnetic radiation acts as a particle, that particle is called a photon.

-The energy E of a photon is related to it is frequency by:

E= h ƒ E=h c/λ• h =constant.• C = the speed of light.• ƒ = the frequency.• λ = lambda is the wavelength.

Radiation intensity and the inverse square law

- All electromagnetic radiation travels at the speed of light and diverges from the source at which it is emitted.

- Intensity is energy flow per centimeter square and is measured in watts per centimeter square (W/cm2).

-The intensity of the radiation decreases with an increase in the distance from the source.

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Radiation intensity and the inverse square law

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-This relation known as the inverse square law, because the intensity is inversely proportional to the square of the distance.

I2 / I1 = (d1/d2)2

I2 = intensity at distance d2

I1 = intensity at distance d1

Radiation intensity and the inverse square law

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Thus, the intensity is inversely related to the distance. If distance from x-ray source is doubled the intensity decreases by a factor of 4.

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inverse square law

Thank you for your attention

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