Hauskbee's 'barometric light' was described as:

Hauskbee's 'barometric light' was described as:

• A. A mercury barometer- that created light by mercury electrons ionizing the gas inside
• B. A neon glow lamp that ionizes gas in neon
• C. A lamp that used mercury electrons to ionize gas inside a sealed tube
• D. A light source using electrical heating of a metal filament

Answer: (A)

Barometric light comes from a discharge in gas that is influenced by the pressure from a mercury barometer. In this device, light is produced when mercury electrons ionize the gas inside a sealed tube, with the mercury column set by atmospheric pressure driving the discharge. The key is the link to the mercury barometer—the light arises because the barometer’s mercury controls the conditions for ionization inside the tube. Neon glow lamps operate by neon gas discharge, not tied to a barometer; a sealed-tube lamp driven by mercury electrons without the barometer aspect misses the barometric influence; a filament lamp emits light from heating, not gas ionization.

Barometric light comes from a discharge in gas that is influenced by the pressure from a mercury barometer. In this device, light is produced when mercury electrons ionize the gas inside a sealed tube, with the mercury column set by atmospheric pressure driving the discharge. The key is the link to the mercury barometer—the light arises because the barometer’s mercury controls the conditions for ionization inside the tube. Neon glow lamps operate by neon gas discharge, not tied to a barometer; a sealed-tube lamp driven by mercury electrons without the barometer aspect misses the barometric influence; a filament lamp emits light from heating, not gas ionization.