Understanding Fluorescent Tube Glow and Plasma
Fluorescent tubes generate light when electricity passes through a gas inside them. This electrical discharge causes the gas to ionize, forming a state known as plasma. This plasma is what directly emits light, typically in the ultraviolet (UV) range.
Plasma: The Glowing Medium
Plasma is often referred to as the fourth state of matter. It's an ionized gas containing charged particles (ions and electrons). In a fluorescent tube:
- An electrical current ionizes the gas, creating plasma.
- The excited atoms within the plasma emit UV radiation.
- This UV light then excites a phosphor coating inside the tube, causing it to emit visible light.
Gas Nature Influences Color
The characteristic color of the light emitted by a fluorescent tube depends significantly on the 'nature of the gas' used. Different gases, when present in the plasma, have unique energy level transitions. When these atoms are excited and return to their ground state, they emit photons of specific wavelengths. This determines the spectrum of the emitted light, influencing the final color observed after interacting with the phosphor coating.
Analysis of Options
- Plasma: This is the state of matter formed in the tube that glows. The specific gases comprising this plasma determine its emission characteristics (color).
- Hydrogen and Helium: These are elements. While specific lamps use pure hydrogen or helium, the question refers to the general phenomenon in a fluorescent tube where the composition of the gas mixture within the plasma dictates the color.
- Bose-Einstein condensate: This is a state of matter occurring at extremely low temperatures, which is unrelated to the high-energy ionization process in a fluorescent tube.
Therefore, the glowing phenomenon in a fluorescent tube, dependent on the specific gases, occurs because the gas forms plasma.
Similar Questions
- When a drop of ink is placed in water, it spreads evenly without stirring. What does this demonstrate?
- Why is a colloid considered stable?
- Why does the palm feel cool when acetone is poured on it?
- What property of gases allows them to fill any container completely?
Important Questions from States of Matter
A liquid is heated up to a certain temperature. Which one of the following situation would correspond to the boiling of the liquid?
Which one among the following oxides has the highest melting point?
Equal volume of all gases, when measured at the same temperature and pressure, contain an equal number of particles. Who proposed the above law?
Match List I with List II and select the correct answer using the code given below the Lists:
Code:List I (Noble gas)
List II (Use)
A. Argon
1. In lights for advertising display
B. Neon
2. Airport landing lights and in light houses
C. Krypton
3. Light in photographer’s flash gun
D. Xenon
4. In tungsten filament to last
Match List-I with List-II and select the correct answer using the code given below the Lists:
List I
(Process)
List II
(Type of change)
A. Heating of camphor
1. Chemical
B. Cooling of water vapor up to room temperature
2. Evaporation
C. Cooking an egg
3. Condensation
D. Formation of water vapor at room temperature.
4. Sublimation
