Question 31: Wood's lamp has a wavelength of –
- A. 320 nm
- B. 300 nm
- C. 360 nm (Correct Answer)
- D. 250 nm
Explanation: ***360 nm***
- A **Wood's lamp** emits **long-wave ultraviolet (UV-A) light**, which is typically in the range of 320 to 450 nm.
- The precise wavelength of **360 nm** is the most common and effective for dermatological diagnostic applications, allowing visualization of specific fluorescence patterns.
*320 nm*
- While 320 nm falls within the UV-A spectrum, it is at the lower end and less characteristic of the peak emission wavelength used in Wood's lamps for diagnostic purposes.
- Using this lower wavelength might result in less pronounced or absent fluorescence for some conditions.
*300 nm*
- A wavelength of 300 nm is in the **UV-B spectrum** which is primarily used for therapeutic purposes like **phototherapy for psoriasis**, not for diagnostic fluorescence with a Wood's lamp.
- UV-B light has different biological effects and is too short to elicit the characteristic fluorescence observed with a Wood's lamp.
*250 nm*
- This wavelength falls into the **UV-C spectrum**, which is **germicidal** and harmful to human tissue.
- UV-C light is not used in Wood's lamps for diagnostic purposes due to its damaging properties and inability to produce the desired fluorescence.