What is the wavelength?
The wavelength of an x ray is at most 10 nano metres downwards, where there is no limit to how short the wavelength of the x ray is.
Does it need a medium?
Electromagnetic waves like x rays do not need a medium to travel, however other waves like mechanical waves do need a medium to travel.
What is it?
An x ray is a form of electromagnetic radiation, thus they do not need a medium to travel. Due to the relationship of how when wavelengths of light decrease, the waves increase in energy, x rays, with their small wavelengths have a higher energy than ultraviolet waves. X rays are usually known for their energy instead of wavelength partially due to its very small wavelength and also due to x ray light tending to act more like a particle than a wave. X ray detectors collect photons of x ray light rather than radio telescopes having large dishes to focus radio waves.
X rays was discovered by Wilhem Conrad Rontgen in 1895, naming it to signify that it is a unknown type of radiation. He discovered x rays when experimenting with vacuum tubes. X rays are seen by having X-ray sensitive film put on the chosen location, and X-rays are shot through that location. At a dentist, the film is put inside your mouth, on one side of your teeth, and X-rays are shot through your jaw. Because bones and teeth are dense and absorb more X-rays then your skin does, silhouettes of bones or teeth are left on the X-ray film while skin appears transparent. Metal absorbs even more X-rays. When the Sun shines on things at a certain angle, shadows are projected onto the ground. Similarly, when X-ray light shines on people, it goes through their skin, but allows shadows of their bones to be projected onto and captured by film.
X rays can also be used for astronomy. In astronomy, things that emit X-rays, black holes are one example, are like the dentist's X-ray machine, and the detector on the satellite is like the X-ray film. X-ray detectors collect individual X-rays, photons of X-ray light, and things like the number of photons collected, the energy of the photons collected, or how fast the photons are detected, can tell us things about the object that is emitting them.
Advantages and disadvantages of x rays
X rays are relatively cheap when compared to similar medical procedures. When a patient requires a medical scan, an X ray costs health insurance plans less than MRI or a CT scan, as well as being cheaper for a hospital to maintain. X-rays are easier to use than MRIs or CT scans. Emergency rooms often have portable X-ray machines to help patients coming in. If a patient requires a MRI or CT scan, either an appointment must be set up or the patient must be transported to a hospital that has this technology readily available.
One disadvantage of X-rays is that they do not give detailed images of the body. MRI or CT scans are excellent tools if the doctor is trying to find a medical issue with organs, bone, the brain, and tissues. X-rays do not give any sort of medical data for organs or tissues, only an image of bones. MRIs and CT scans can show far more bone detail than X-rays. X rays also will pose a problem of radiation exposure, where exposure to X rays over a long period of time can lead to tissue damage.
Sources: http://www.ehow.com/list_6939750_advantages-disadvantages-x_rays.html , http://science.hq.nasa.gov/kids/imagers/ems/xrays.html , http://health.howstuffworks.com/medicine/tests-treatment/x-ray.htm