Which of the following statements about X-rays is correct? X-rays

Step 1: Analyze the question We need the true statement about X-rays. Let's check each option.

Step 2: Key concept X-rays are produced in an X-ray tube. Electrons are emitted from a heated cathode and accelerated by a high voltage. They strike a metal target (anode, e.g. tungsten) and are suddenly stopped. Their kinetic energy is converted mostly into heat (about 99%) and a small part into X-ray photons. X-rays are high-frequency, short-wavelength electromagnetic waves.

Step 3: Check each option

• A. Produced when a metal surface is irradiated with ultraviolet light. False. That describes the photoelectric effect, which emits electrons, not X-rays.
• B. Produced when a metal target is used to block fast moving electrons. True. This is exactly how X-rays are produced (bremsstrahlung, or "braking radiation", plus characteristic X-rays).
• C. Have long wavelengths and are therefore very penetrating. False. X-rays have short wavelengths (about 10⁻¹⁰ m), and that is why they are penetrating.
• D. Are not part of the electromagnetic spectrum. False. They lie between ultraviolet and gamma rays on the spectrum.

Step 4: Answer

Tip: Remember "X-rays = fast electrons STOPPED by a metal target." Also remember that X-rays are short-wavelength, high-energy waves. Whenever an option says "long wavelength" for X-rays, it is wrong.