đ Key Concepts
⢠Review how an incandescent bulb produces light (heated filament vs. gas discharge).
⢠Compare which fixtures in the illustration use a filament only versus a discharge tube with ballast.
⢠Notice which lamp circuit does not require a ballast or igniter to operate from the AC supply.
đ Think About
⢠Looking at each labeled fixture AâD, which one shows a simple filament inside the glass envelope instead of an arc or discharge tube?
⢠Which of the four circuits is directly connected to the voltage source without any special ballast, igniter, or transformer components?
⢠Among MBF, SOX, and SON lamps, which types are known to be gasâdischarge lamps rather than incandescent? What does that leave as the incandescent option?
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Before You Answer
⢠Verify which diagram explicitly labels a wire filament as the lightâproducing element.
⢠Check which fixtures (B, C, D) mention components like ballast, igniter, or discharge tubeâthese are typical of gasâdischarge lamps, not incandescent bulbs.
⢠Confirm that the remaining fixture matches the construction youâd expect for a standard incandescent lamp: screw cap, filament, support wires, and no external control gear in the circuit.