Mercury-vapor lamp

A mercury-vapor lamp is a type of light bulb that uses electricity to make light. Inside the bulb, there is a gas called mercury, which is kind of like a liquid metal. When electricity flows through the bulb, it heats up the mercury gas, which turns into a type of light called ultraviolet (UV) light.

The UV light is not visible to our eyes, so the bulb also has a special coating inside that turns the UV light into visible light that we can see. This makes the bulb look like it's shining with a bright, blueish-white light.

Mercury-vapor lamps are often used in outdoor streetlights, in parking lots, and in sports stadiums, because they give off a lot of light and last a long time. However, they also use a lot of energy and can be dangerous if the bulb breaks and the mercury gas is released, so they have to be handled carefully.