R1-4 Incandescent Lamps

• The filament is made from tungsten, which has high melting point.
• Filaments are coated with oxide to increase thermal resistance and prevent evaporation.
• How does incandescent light work?

  Produces light by passing electric current through a filament and heating it until it glows (incandescence)
• Incandescent lamps have low efficiency because most energy goes into heat rather than visible light
• How much energy input is wasted as heat with incandescents?

  about 90%
• What are filaments made of?

  Tungsten, which has a high melting point and low rate of evaporation
• What happens when operating temperature of filament is higher?

  It burns brighter, but also has shorter lifespan
• What kind of glass is used with tungstgen-halogen lamps?

  Quartz, because it can withstand very high temperatures
• What is the lamp base?

  Bottom of the lamp that connects the filament to the electrical supply
• How are bulb size and shape designated?

  By a letter and number. Letters indicate shape, numbers indicate the largest diameter of the bulb in eighths of an inch
• What is the tungsten filament shape?

  A straight wire, coil or coiled coil
• What are the lead in wires of a bulb?

  Carry the current to and from the filament. The neutral connects to the outer base shell, hot wire connects to the base contact
• What gas are used in incandescent bulbs?

  A mixture of nitrogen and argon, which will mix with the tungsten filament to produce light when turned on
• What is the base contact of the incandenscent?

  Point of contact with the hot wire
• How is a parabolic different from a reflector bulb?

  Reflector is larger
• What are the code letters for each shape?

  1. Straight side - S
  2. Flame-shaped - F
  3. Globular - G
  4. Standard line - A
  5. Tubular - T
  6. Pear-shaped - PS
  7. Parabolic - PAR
  8. Reflector - R
• When is clear glass ideal?

  Where good optical control is required (will produce clear shadows)
• Which type of bulb glass is best for normal sight conditions?

  Diffuse glass. It reduces brightness and glare of the light by increasing surface area of the bulb
• How do coloured glass bulbs work?

  The coloured glass absorbs all but the desired colour, which is transmitted through the glass
• Do lamp bases have different associated wattage ratings?

  Yes
• What is the Medium lamp base also known as?

  Edison base
• What is the most commonly used base for general lamp service?

  Edison base / screw type, medium size
• Where must you connect the screw shell?

  To the neutral / identified conductor, never to the hot wire (black to centre, white to screw shell)
• Incandescent lamps have a ____ temperature coefficient.

  positive....When lamp is cold, it draws more current than when it is warm due to low initial filament resistance. As filament heats up, its resistance increases, reducing the current flow
• High wattage lamps have a _____ efficacy than low-wattage lamps of the same voltage

  Higher
• General service lamps may be burned in any position, but are most effective when burned with the base pointing ___

  up
• Long-life lamps are designed to operate at _____ voltages than they would normally receive, thereby extending lamp life

  higher
• Which type of lamps have a better regenerative cycle?

  Tungsten-halogen lamps
• What glass do tungsten-halogen lamps use?

  Quartz. It's also known as a quartz halogen or quartz-iodine lamp
• Which lamps have a high lumen maintenance?

  tungsten-halogen lamps
• what is the regenerative cycle?

  prevents glass from blackening and results in the high lumen maintenance of the lamp. In tungsten-halogen lamps, the halogen gas combines with the evaporated tungsten and allows it to drift back to the filament by convection (tungsten re-deposited on the filament)
• Do tungsten-halogen lamps make a good spotlight or automotive headlight?

  Yes
• What colour light source is produced well by tungsten halogen lamps?

  White light
• Is it okay to use dimmers on tungsten halogen / quartz halogen lamps?

  They can be used, but they must occasionally be operated at full voltage to permit the regenerative cycle to prevent the lamp from darkening
• What are infrared heat lamps used for?

  Best for creating heat
• Why are heat deflectors used in some lamps?

  They are used in higher-wattage lamps to reduce circulation of hot gases into the bulb
• what condition is finger contact with cold quartz glass likely to cause?

  premature glass breakage and/or glass discolouration
• when would a pre-focus lamp base be used?

  for projectors, where you need precise light