Q26.Marks: +2.0UGC NET Paper 2: Computer Sc 6th Jan 2025 Shift 1
The light given off by the phosphor during exposure to the electron beam is known as
1.Fluorescence✓ Correct
2.Phosphorescence
3.Persistence
4.Retracing
Solution
The correct answer is Fluorescence.
Key Points
Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation.
It is a form of luminescence.
In a cathode ray tube (CRT) or other similar devices, when the phosphor coating is struck by the electron beam, it emits visible light through the process of fluorescence.
This emission of light occurs almost instantaneously with the exposure to the electron beam.
Fluorescence ceases almost immediately when the excitation source (electron beam) is removed.
This characteristic makes it suitable for applications requiring quick response times.
Additional Information
Phosphorescence, on the other hand, involves a delayed emission of light and continues to glow even after the excitation source is removed.
Persistence refers to the duration the screen continues to emit light after the electron beam has moved on.
Retracing is the process where the electron beam returns to the beginning of the next line or frame in a CRT display.
