Lighting Types Flashcards
Explain how flourescent lamps work
Current is conducted through mercury vapour. This results in mostly ultra violet light being produced. A phosphor coating on the outside of the lamp converts the UV into visible light. By having different types of phosphors different combinations of wavelengths can be created and hence different colour rendering.
Explain the colour rendering problems with flourescent lamps
Because phosphors will necessarily output a narrow band of light then combinations of phosphors will only output spikes of wavelengths bu not a continuous spectrum like GLS.
Explain metal hallide lamps
Other metals are mixed in with the mercury vapor. The light output comes directly from other metal ions with the need for flourescent phosphors. UV is filtered out by the glass. The combinations of metals can change the colour properties.
Describe the advantages and disadvantages of LED luminaires
Higher efficacy although may still be worse value than the best flourescents. Small in size so can be incorporated into architectural details and furniture. Easily dimmed. Very long life. The output decays rather than failing like GLS.
