Wilhelm Conrad Roentgen, a German physicist, is famous for discovering which type of penetrating radiation used in medical and industrial imaging?

Introduction / Context:

Electromagnetic radiation covers a wide spectrum, from radio waves to gamma rays. Among these, X rays are especially important in medicine and engineering because they can pass through soft tissue and thin materials while being absorbed by denser substances. This question asks you to identify which type of radiation Wilhelm Conrad Roentgen discovered, a basic fact in science and inventions related to health technology.

Given Data / Assumptions:

• The scientist in question is Wilhelm Conrad Roentgen.
• The question asks which type of radiation he discovered.
• The options list several areas of the electromagnetic spectrum.
• You are expected to match Roentgen with the correct region of this spectrum.

Concept / Approach:

In 1895, Roentgen was experimenting with cathode ray tubes when he observed that a fluorescent screen in his laboratory glowed even though it was shielded from direct light. He concluded that a new, previously unknown type of radiation was being produced, which he named X rays, with X standing for unknown. These rays could pass through many materials and produced images of bones and internal structures on photographic plates. This discovery earned Roentgen the first Nobel Prize in Physics. Ultraviolet, infrared, gamma rays and microwaves are other parts of the spectrum, but their discovery histories involve different scientists, not Roentgen.

Step-by-Step Solution:

Verification / Alternative check:

Physics textbooks, medical radiology histories and Nobel Prize records all state that Roentgen discovered X rays in 1895. The famous early X ray image of his wife hand, showing her bones and wedding ring, is often reproduced in these sources. Other parts of the electromagnetic spectrum are attributed to different scientists. This consistent documentation confirms that X rays are the correct choice for this question.

Why Other Options Are Wrong:

Ultraviolet rays were studied earlier by several scientists including Johann Ritter and others, not by Roentgen as a new discovery.

Gamma rays were later identified by researchers working on radioactivity, such as Paul Villard and Ernest Rutherford.

Infrared radiation was discovered earlier by William Herschel when he measured heating beyond the red end of the visible spectrum.

Microwaves became important in twentieth century communications and radar, with different scientists and engineers involved in their use.

Common Pitfalls:

Some candidates may confuse X rays and gamma rays because both are penetrating and high energy. However, the name Roentgen is specifically tied to X rays. A useful memory aid is that some countries once used the unit roentgen to measure X ray exposure, directly linking his name with this type of radiation.

Final Answer:

Wilhelm Conrad Roentgen discovered X rays.