Science Milestones: The X-Ray

On 8 Nov, 1895, Wilhelm Conrad Röntgen discovered an image projected far beyond the possible range of the cathode rays (now known as an electron beam) cast from his cathode ray generator. Further investigation showed that the rays were generated at the point of contact of the cathode ray beam on the interior of the vacuum tube, that they were not deflected by magnetic fields, and they penetrated many kinds of matter.

x-raysA week after his discovery, Röntgen took the very first picture using X-rays of his wife Anna Bertha’s hand. When she saw her skeleton she exclaimed “I have seen my death!”   The photograph electrified the general public and aroused great scientific interest in the new form of radiation. Röntgen named the new form of radiation X-radiation (X standing for “Unknown”), hence the term X-rays.



Wilhelm Conrad Röntgen was born on March 27, 1845.  He first attended the Federal Polytechnic Institute in Zurich as a student of mechanical engineering and graduated with a Ph.D. from the University of Zurich in 1869.

Röntgen was married to Anna Bertha Ludwig and had one child, Josephine Bertha Ludwig.  Röntgen died on 10 February 1923 from carcinoma of the intestine. It is not believed his carcinoma was a result of his work with ionizing radiation because of the brief time he spent on those investigations, and because he was one of the few pioneers in the field who used protective lead shields routinely.

Like other contemporaries, Röntgen did not take patents out on his discoveries and donated the money for his Nobel prize to the University of Würzburg. Following World War I, he fell into bankruptcy, He spent his final years at his country home near Munich. In keeping with his will, all his personal and scientific correspondence were destroyed upon his death.

In honor of his accomplishments, the International Union of Pure and Applied Chemistry named element 111, Roentgenium, a radioactive element with multiple unstable isotopes, after him in 2004.

The Electromagnetic Spectrum

Almost everything that we know about distant objects in the universe comes from studying the light that is emitted or reflected by them. The entire range of energies of light is called the electromagnetic spectrum. Arranged from high energy, short wavelength to low energy, long wavelength, the electromagnetic spectrum is divided into gamma rays, x-rays, ultraviolet, optical (visible light), infrared, microwaves, and radio waves.  All electromagnetic waves travel at the same speed in space. Our eyes are sensitive only to a narrow band of electromagnetic radiation called visible light.  To learn more about the spectrum, NASA has a great website devoted to the Chandra X-ray Observatory with photographs and activities you can download for free.

In medicine, an x-ray is sometimes used to produce images of the structures inside the body. Because of their short wavelength, x-rays can pass through the body, but are absorbed in varying amounts depending on the density of the material they’re passing through. This is why bones appear white on x-ray images. They are the most dense, and therefore block the most x-rays from getting through; muscle and fat are less dense, and appear in varying shades of gray; the air in between is not very dense at all, and shows up black. X-rays are often used to quickly examine the bones and teeth. Sometimes a contrast medium—such as iodine or barium—is introduced to provide more detail in the chest and abdomen, as well. This substance blocks x-rays and shows up white on x-ray.

A computed tomography scan or CAT-scan uses x-rays to create images of the body. However, an x-ray and a CAT-scan show different types of information. An x-ray is a two-dimensional picture and a CAT-scan is three-dimensional. By imaging and looking at several three-dimensional slices of a body (like slices of bread) a doctor could not only tell if a tumor is present, but roughly how deep it is in the body.

Bring it Home

  • Visit your doctor or dentist and ask to see our own x-rays
  • Do a Google search of x-ray images and compare the skeletons of different animals
  • Obtain a set of old x-rays (with patients’ identifying information removed) and use it identify and label the skeletal system (large windows work well as light boxes)

Science Milestones

Visit my Science Milestones page to learn more about scientists whose discoveries and advancements have made a significant difference in our lives or who have advanced our understanding of the world around us.

To find out about more people born in March hop on over to iHomeschool Network’s March birthdays page.

Science Milestones: Who Invented the Bunsen Burner?

The Bunsen Burner, is a common piece of laboratory equipment that produces a single open gas flame used for heating, sterilization, and combustion was invented by German chemist Robert Wilhelm Eberhard von Bunsen on March 31, 1811. Working alongside his lab assistant, Peter Desaga, he designed a burner with a hot, sootless, non-luminous flame by mixing the gas with air in a controlled fashion before combustion. Bunsen burners are now used in laboratories all around the world. The device in use today safely burns a continuous stream of a flammable gas such as natural gas (generally methane) or a liquefied petroleum gas such as propane, butane, or a mixture of both.

bunsen burner

Subscribers to my newsletter will receive the download link to my Burning Sugar Lab (pictured above).


Robert BunsenRobert Wilhelm Eberhard von Bunsen was born on March 30, 1811 at Göttingen in 1811, in what is now the state of Lower Saxony in Germany (though there are some documents stating the 31st). Bunsen was the youngest of four sons of the University’s chief librarian and professor of modern philology, Christian Bunsen. He investigated emission spectra of heated elements, and discovered caesium (in 1860) and rubidium (in 1861) with Gustav Kirchhoff. He also developed several gas-analytical methods, was a pioneer in photochemistry, and did early work in the field of organoarsenic chemistry.

Bunsen was one of the most universally admired scientists of his generation. A master teacher, he always conducted himself as a perfect gentleman, maintaining his distance from theoretical disputes. He much preferred to work quietly in his laboratory, continuing to enrich his science with useful discoveries. As a matter of principle he never took out a patent. He retired at the age of 78 and thereafter pursued his interests in geology and mineralogy. He died in Heidelberg at the age of 88.

Bring it Home

Upon reading about Eberhard von Bunsen and his invention, I really wanted an opportunity for my kiddos to experience using a Bunsen burner. However, as you can guess, a Bunsen Burner is not typically available to homeschool families unless you have access to a high school or college science lab. If this is a possibility for you and you are interested in learning how to use one safely, the video Introduction to the Bunsen Burner provides a great introduction. It also discusses typical lab applications and safety precautions.

As an alternative, there are many hands-on lab activities that can be done safely in your home with simply a candle or Sterno Cooking Fuels. Here are a few ideas that you may wish to explore at home.

    • Burning Sugar Lab – Observe the chemical changes that take place when sugar is exposed to heat
      Subscribers to my newsletter will receive the download link to my Burning Sugar Lab (pictured above)
    • Flame Photometry – Discovering the Emission Spectrum
    • Observe a Candle
      • What happens to the candle when you light it?
      • Can you prove that the candle needs oxygen in order to burn?
      • Can you prove that the candle produces carbon dioxide when it burns?
      • What happens when you hold a piece of glass in different parts of the flame? What do these results say about the process of burning wax in a candle?
      • Is it possible to light a candle without touching the flame directly to the wick? Why or why not?
      • Sketch and label the flame. What part of the flame is the hottest?
      • Design an inquiry experiment to compare different brands of commercial candles?

Science Milestones

Visit my Science Milestones page to learn more about scientists whose discoveries and advancements have made a significant difference in our lives or who have advanced our understanding of the world around us.

To find out about more people born in March hop on over to iHomeschool Network’s March birthdays page.

Science Milestones: Van de Graaff Generator and Tesla Coil

Last week, three local utility company employees (two of whom were linemen) spent the morning with us sharing stories and giving demonstrations about energy conservation and electrical safety.  It was a fun-filled atmosphere and everyone learned something new.

zap wow

While the lineman were giving their presentation and interacting with the kids, I was as giddy as a school girl.  I recognized the electrical “toy” on the table and was eager to play with it and allow the kids the same opportunity.   As a former teacher in a public school, I had had some experience with a Van de Graaff generator, a device that looks like a big aluminum ball mounted on a pedestal, as a source of artificial high-voltage discharges.  They are great fun in the classroom because when you touch the ball, it makes your hair stand on end as the negatively charged particles build up and push away from one another.  But as a homeschool mom, a Van de Graaff generator just isn’t in our homeschool budget.  I was in for a surprise, however, for the device was not what I thought it was – it was a higher voltage Tesla coil.

Van de Graaff Generator

To understand the Van de Graaff generator and how it works, you need to understand static electricity. Almost all of us are familiar with static electricity because we can see and feel it in the winter. On dry winter days, static electricity can build up in our bodies and cause a spark to jump from our bodies to pieces of metal or other people’s bodies. We can see, feel, and hear the sound of the spark when it jumps. You may have also done some experiments with static electricity.

A Van de Graaff generator is a device designed to create static electricity and make it available for experimentation. The American physicist Robert Jemison Van de Graaff invented the Van de Graaff generator in 1931. The device that bears his name has the ability to produce extremely high voltages — as high as 20 million volts. Van de Graaff invented the generator to supply the high energy needed for early particle accelerators. These accelerators were known as atom smashers because they accelerated sub-atomic particles to very high speeds and then “smashed” them into the target atoms. The resulting collisions created other subatomic particles and high-energy radiation such as X-rays. The ability to create these high-energy collisions is the foundation of particle and nuclear physics.

Van de Graaff generators are described as “constant current” electrostatic devices.  In the case of the Van de Graaff generator, as you approach the output terminal (sphere) with a grounded object, the voltage will decrease, but the current will remain the same. Conversely, batteries are known as “constant voltage” devices because when you put a load on them, the voltage remains the same. A good example is your car battery. A fully charged car battery will produce about 12.75 volts. If you turn on your headlights and then check your battery voltage, you will see that it remains relatively unchanged (providing your battery is healthy). At the same time, the current will vary with the load. For example, your headlights may require 10 amps, but your windshield wipers may only require 4 amps. Regardless of which one you turn on, the voltage will remain the same.

Tesla Coil

A Tesla coil is an electrical resonant transformer circuit invented by Nikola Tesla around 1891. It is used to produce high-voltage, low-current, high frequency alternating-current electricity. Tesla coils can produce higher voltages than electrostatic machines like the Van de Graaff generator described earlier.  Tesla used these coils to conduct innovative experiments in electrical lighting, phosphorescence, X-ray generation, high frequency alternating current phenomena, electrotherapy, and the transmission of electrical energy without wires.

The lineman demonstrated the coil but didn’t offer the kids a chance to try it for themselves.  When most had departed though, I approached and inquired if I couldn’t give it a go.  I was in for quite the shock!

If you are interested in exploring electricity in more depth in your homeschool, I encourage you to reach out to your local schools. It may be possible to visit a science lab at your local middle school or high school to experience a Van de Graaf generator first hand.  Many science centers also have them and even if not on public display, may be willing to organize a special class for a group of homeschoolers.  Alternatively, contact your local utility company as I did.  They may have special programs they can bring to your co-op.  You won’t know if you don’t ask.