Which two electromagnetic waves are useful for diagnosing illnesses?
- x-rays and radio waves
- microwaves and gamma rays
-gamma rays and x-rays
-radio waves and ultraviolet waves

answer is a (x rays and radio waves)

Radio waves, everyone seems to forget, are important in Nuclear Magnetic Resonance Imaging, i.e. MRI (in hospitals they drop the N of nuclear not to scare people. although NMR has nothing to do with radioactivity, but rather nuclei spins). In NMR and MRI the frequency of the EM waves involved are in the hundreds of Mhz.Microwaves are now involved mainly in Microwave thermotherapy. Basically this technique uses microwaves to destroy excess tissue and it is mainly used for certain bladder or intestinal problems.Infrared light is used in some detection techniques such as IR scans, but also in emerging Infrared therapies. Also some laser surgery and laser scanning techniques use IR light since it has lower energy than visible light. For scans, such a retinal tomography scans low power lasers are used of course.Visible light has many applications. The main one beyond “human vision” is laser technology, such as laser surgery.Ultraviolet light is used to sterilizeequipment. In addiction some kinds of skin conditions can improve with the exposure of ultraviolet light. This is called phototherapy. This uses usually UVA (lowwer energy UV) in combination wi5th a sensitizer like psoralen. Phototerapy also helps sometimes against inflammation and infections.X-rays are used in common X-ray photography(e.g. for broken bones) or for X-ray Computer Tomography (CT scans). X-ray are also used as therapy against cancer, where usually focused beams are used to destroy a tumor or a diffuse irradiation to fight metastasis. This is called radiotherapy.γγ-rays are used in PET Scans (positron emission tomography). Here the γγ-rays are formed when the positrons from the radionuclide (i.e. radioactive elements - in this case positron emitters) hits an electron and annihilates, giving out γγ-rays. These γγ-rays are then detected. Sometimes these are also used to kill cells, usually through injecting radionuclides which emit gamma rays in what is also usually called radiotherapy.

Multiply the 3 dimensions, assuming it is a rectangular cuboid, to get the volume in cm³ divide mass by volume to get density in g/cm³