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Electromagnetic Spectrum Activity - X-rays

Resources

• NASA EM Spectrum Information Pages X-rays
• Discovery Education EM Spectrum
• List of SI (metric) prefixes . e.g. nano, milli, mega, tera.

X-rays are a band of the EM spectrum that many of us have experienced in a medical environment. X-rays have more energy than ultraviolet light but less than gamma rays. X-rays are ionizing radiation. Ionizing radiation has enough energy to tear electrons away from their atoms. The atoms are now 'ions'. These ions can cause unwanted chemical reactions in a material or organism.

With shorter wavelengths it is more common to refer to the wave's wavelength rather than its frequency. X-rays covers the range from 0.01 to 10 nm (nm = nanometers = 1x10-9). The frequency would be expressed in Phz (Petahertz) or Ehz (exahertz) . A high frequency wave has a short wavelength. The relationship is defined as:

• Variables:   λ=wavelength (m)     v = speed of light (3 x 108 m/s)     f = frequency (Hz). Note EHz = 1 x 1018 Hz
• Formula:   λ = v ÷ f
• Example:   λ = 3 x 108 m/s ÷ 3 EHz = 0.1 nm

In nature, X-rays are made by objects in space such as stars, supernova and black holes. Humans make x-rays by using high voltage (up to 150,000 volts) to slam electrons into a metal, often titanium. The movement of electrons in the target metal generates the x-rays. The typical use of x-rays is to look through optically opaque objects, such as you! The x-rays travel trough an object and strike a photographic film or sensor. The strength of the image generated is related to the density of the object being x-rayed.

Another use of x-rays was made famous by the discover of the structure of DNA. Rosalind Franklin used x-ray crystallography to determine the double helix structure of DNA.

EM Spectrum Data Table

Name Wavelength Range Wavelength
(comparative size)
Frequency Range Energy
ionizing/ med / lo
Sources Uses
X-rays

Waves Glossary

Electromagnetic waves
Radiation consisting of waves of energy sent through space and matter associated with electric and magnetic fields resulting from the acceleration of an electric charge (light, x-rays, microwaves, gamma rays, etc.). 3.9
Frequency
The number of back-and-forth cycles per second, in a wave or wave-like process. 3.5
Period
The time for one wavelength to pass a point. The time for a wave to travel the distance of one wavelength. P= 1/frequency. 3.5
Wave
A rhythmic disturbance that transfers energy from place to place. 3.5
Wavelength
The distance measured from crest to crest of one complete wave or cycle. 3.5