Gas Discharge Tubes: Shedding Light on Specific Frequencies

How do gas discharge tubes emit electromagnetic radiation of specific frequencies?

A gas discharge tube emits specific frequencies of electromagnetic radiation when electrons, accelerated by a high voltage from the cathode to anode, excite gas atoms.

Why is a high potential difference necessary across the tube?

A high potential difference is required to provide the necessary energy for this excitation.

Answer:

A gas discharge tube emits specific frequencies of electromagnetic radiation when electrons, accelerated by a high voltage from the cathode to anode, excite gas atoms. A high potential difference is required to provide the necessary energy for this excitation.

Gas discharge tubes are fascinating devices that emit specific frequencies of electromagnetic radiation. These tubes contain a rarefied gas between two metal electrodes. When a high voltage is applied across the tube, electrons are emitted from the cathode and accelerated towards the anode. This acceleration provides the energy needed to excite the gas atoms in the tube.

As the high-energy electrons collide with gas atoms, the atoms become excited and emit radiation as they return to their ground state. Each type of gas emits radiation of specific frequencies, which results in the different colors observed in gas discharge lamps like neon lights.

The high potential difference is crucial in this process as it provides the energy required to excite the gas atoms enough to emit visible radiation. This principle is not only seen in gas discharge tubes but also in devices like cathode-ray tubes (CRTs) in older television and computer screens, as well as in the production of X-rays.