Kids' Science Challenge #7 Question 3. What very useful phenomenon, now used extensively as a diagnostic tool by physicians, was discovered accidentally by the German scientist William Roentgen? Answer: X-Rays When Wilhelm Roentgen (1845-1923) discovered that X-rays could pass through human tissue and darken photographic plates, he was simply studying the electrical nature of matter and had not expected to discover a dramatic new tool for medical and other uses. During his investigations he observed the same thing that others had seen but, making an intuitive leap of understanding, recognized a fascinating discovery. Correct answer received from: Jimmy D., Hamish R., Joe, Irana M., Dino, Matt C., Krissy, Nikhil, Amanda M.,