Physics 2015 JAMB Past Questions - Question 5: The ray which causes gas molecules to glow is known as

Correct Answer

D

Explanation

The ray which causes gas molecules to glow is known as an "excitation" or "excitation radiation."
The phenomenon where gas molecules emit light when they are excited is known as "luminescence." This can happen in several ways, and the type of ray or energy source that causes gas molecules to glow depends on the specific process involved. Here are a few examples:

1. Electromagnetic radiation: Gas molecules can emit light when they are exposed to electromagnetic radiation, such as ultraviolet (UV) light, X-rays, or gamma rays. This is known as photoexcitation or photoluminescence.

2. Electric discharge: In devices like neon signs, gas molecules can glow when an electrical discharge, typically in the form of a high-voltage electrical current, excites the gas inside the tube. This is called electroluminescence.

3. Heat: Some gases can glow when they are heated to high temperatures. For example, incandescent light bulbs use a heated filament to produce visible light.

4. Chemical reactions: Chemiluminescence is a process in which gas molecules emit light as a result of a chemical reaction. Fireflies and certain chemical glow sticks are examples of this phenomenon.

5. Particle bombardment: When high-energy particles, such as electrons or ions, collide with gas molecules, they can excite the gas, causing it to emit light. This is seen in devices like cathode ray tubes and some types of gas discharge lamps.

In summary, the type of ray or energy source that causes gas molecules to glow can vary depending on the specific mechanism of luminescence involved. It could be electromagnetic radiation, electrical discharge, heat, chemical reactions, or particle bombardment, among others.