*You can read this article in Turkish.


-Yes Sinan tell us, what is the speed of sound waves in the space?

-Sir, sound waves are kind of a mechanic wave and they can not travel in the empty space.

Oh my God, I still have goosebumps when I remember my iconic answer to the professor that day! That was the most charismatic answer I have given to anybody in my entire life. How did it come to my mind, how did I knew it I don’t remember, I don’t remember if I have read about it before. The professor was waiting to receive the answer “343.2 meter/second” which is the speed of sound waves in the atmosphere but I didn’t gave him what he asked for.

X-rays which we will discuss in this topic are one kind of a wave too. Waves are divided into two sub categories called mechanic and electromagnetic. Mechanic waves such as sound waves need a medium like water or air for transferring their energy. On the other hand, X-rays are electromagnetic waves and they do not necessarily need a medium for travelling. Electromagnetic waves, as you can understand from their name are consisted of electrical and magnetical medium components and they travel in the space with the speed of light “c”.

The wavelength of X-rays are around 10-10 meters.  This is such a short wavelength, and waves with short lenghts have high frequencies and they create high energy. This is a universal physics law and you can observe it via the Figure.1 found above.

Figure 1-Electromagnetic Spectrum

As you already know X-rays have various uses in our daily life and I will explain some of them through a physicist point of view in the oncoming paragraphs.

Roentgen filming is possible due to the fact that X-rays can pass through the matter. The amount of passing through changes with the properties of the medium. For example X-rays can easily pass through less dense medium like wood and flesh but when it comes to denser medium like lead X-rays can not easily pass through.

Transmissivity of X-rays depend on the energy it contains. The most energetic of the X-rays are called hard X-rays and they have higher frequency. Whereas soft X-rays are the ones that have lower frequency and energy. When X-rays pass through your arm it shows the inner structure of the tissues and it draws a picture on the photograph plate or a fluorescent screen due to the relative density of the tissues it passes.

X-rays are also used in radiotherapy. Rather than using low doses of X-rays like in filmography, this treatment uses a high dose of X-rays to shrink the tumours and kill cancerous cells. But it is known that there is a correlation between developing cancer and exposure to X-rays, so this method is highly controversial.


*This article has been translated into English by Selma Çam for Post-Line.

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