Dermatological Procedures — MCQs

Question 41: What is the wavelength of ultraviolet (UV) rays used in a Woods lamp for dermatological examination?

• A. 360 nm (Correct Answer)
• B. 460 nm
• C. 660 nm
• D. 760 nm

Explanation: ***360 nm*** - A **Woods lamp** uses **long-wave ultraviolet A (UV-A)** radiation, which typically ranges from **320 to 400 nm**. - **360 nm** falls within this range and is the approximate peak wavelength used to induce fluorescence in various dermatological conditions. *460 nm* - This wavelength falls in the **visible blue light spectrum**, not the ultraviolet spectrum. - While visible light can be used for examination, it does not induce the characteristic fluorescence observed with a Woods lamp. *660 nm* - This wavelength is in the **visible red light spectrum**. - Red light is not used in a Woods lamp for dermatological diagnostic purposes, as it does not produce the necessary fluorescence. *760 nm* - This wavelength falls into the **near-infrared spectrum**, which is beyond visible light and the UV range. - Infrared radiation has different applications in medicine but is not used in a Woods lamp.