electrical4u.com logo Home MCQ Engineering Calculators Videos Basic Electrical Circuit Theories Electrical Laws Materials Batteries Illumination Generation Transmission Distribution Switchgear Protection Measurement Control System Utilities Safety Transformer Motor Generator Electrical Drives Electronics Devices Power Electronics Digital Electronics Biomedical Instrumentation

Why is Fluorescent Lamp Phosphor Coated?

Published on 24/2/2012 & updated on Monday 14th of May 2018 at 12:53:37 PM
Fluorescent Lamp is still the mostly used light source in our day to day life. It illuminates the very eye pleasant light. For producing eye pleasant light phosphor is used inside of the fluorescent lamp. It is used to convert ultraviolet ray radiation into visible radiation. Previously zinc beryllium silicate was used as the basic phosphor. Later contemporary lamps had used the phosphor that was the mixture of calcium halophosphate and magnesium tungstate. This version of phosphor coating produced yellowish white light but later bluish white. But now a day’s Phosphor is actually a semiconductor material that has been mixed with activators. It has peak spectral sensitivity near 253.7 nm. In its band theory, we can see the three zonal bands; they are valence band, forbidden band, and the conduction band. In addition of activators with phosphor material a permitted energy level is created in the forbidden zone. One example of the activator is silver.

The ultraviolet ray to visible ray conversion is shown pictorially below.phosphor model of zinc sulfide

Phosphor Model of Zinc Sulfide

Related pages
Why is Fluorescent Lamp Phosphor Coated?

A - B :- Electron Jump B - E :- Electron Migration E - D :- Electron Jump D - C :- Electron Jump A - C :- Hole Migration

Please Rate this Article
⚑ 0 total

New Articles
More Articles on Illumination Engineering
LampsTheory of LightSources of LightMaterialLighting SchemePhotometer
Articles Categories
Write for Us
Basic Electrical
Electric Transformer
Electric Generator
Electric Motor
Electrical MCQ
Engineering Calculators
Video Lectures
Electrical Generation
Electric Transmission
Electric Protection
Electrical Measurement
Electronics Devices
Power Electronics
Digital Electronics