Mercury light is not a single wavelength, but rather a spectrum of wavelengths. This means it contains multiple different colors, each with its own unique wavelength.

Here's a breakdown:

* Mercury vapor lamps: These are the most common type of "mercury light". They emit a distinct blue-green light that is actually composed of several strong spectral lines:

* Ultraviolet (UV): While not visible to the human eye, mercury vapor lamps also emit significant UV radiation, particularly at 254 nm.

* Visible: The most prominent visible lines are:

* 404.7 nm (violet)

* 435.8 nm (blue)

* 546.1 nm (green)

* 577.0 nm & 579.1 nm (yellow)

* Infrared (IR): Mercury vapor lamps also emit some infrared radiation.

* Other mercury light sources: Other types of mercury lamps, like high-pressure mercury lamps, can have more complex spectra with additional wavelengths.

Therefore, it's impossible to give a single number for the "number of wavelengths" in mercury light. Instead, it's a mixture of different wavelengths, including ultraviolet, visible, and infrared.