Ultraviolet lamps must produce UV radiation in which wavelength interval?

Ultraviolet lamps used for tanning must produce UV radiation within the wavelength interval of 200 to 400 nanometers. This range is significant because it encompasses both UVA and UVB wavelengths, which are essential for tanning. UVA radiation, which falls between approximately 320 to 400 nanometers, penetrates deeper into the skin and is primarily responsible for tanning and long-term skin damage. UVB radiation, ranging from about 290 to 320 nanometers, is known for its role in producing vitamin D and contributing to the immediate tanning effect and sunburn.

The correct answer captures the full spectrum of UV radiation relevant to tanning and skin health, ensuring that the lamps are effective for their intended purpose while also emphasizing safety awareness.