đ Key Concepts
⢠Difference between incandescent lamps and discharge lamps (like sodium or mercury vapor)
⢠Role of a filament in producing light vs. an arc discharge tube with electrodes and ballast
⢠How an incandescent lamp connects directly to the supply without needing a ballast or igniter
đ Think About
⢠Look at each figure in the illustration and decide which one shows light being produced by a heated wire rather than by an electrical discharge through gas or vapor
⢠Compare which circuits include extra components such as a choke coil, transformer, ballast, or igniter, and which one could run directly from the supply
⢠Focus on the construction labels: which lamp mentions a filament, and which ones describe discharge tubes, sodium retention, or mercury vapor?
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Before You Answer
⢠Identify the figure that clearly shows a wire filament as the main lightâproducing element
⢠Confirm that the same figure does not require a ballast, transformer, or igniter in its circuit to operate
⢠Verify that the other figures use terms like discharge tube, sodium, mercury vapor, or ballast, which indicate gasâdischarge (not incandescent) lamps