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Question:

Electrical transformers and lightbulbs?

If the primary circuit of a transformer is connected to a power source and the secondary circuit has a light bulb, will the light bulb turn on and stay on when the power source is turned on? Or will it turn on for a few seconds and then turn off?This question's been bugging me because I think because transformers are usually wired through AC that the bulb would only turn on for a few seconds and then turn off, but then shouldn't current be constantly flowing so it would stay on?Thanks for and clarifications.

Answer:

ok if you connect the transformers primary to your household wiring that is AC means alternating current. since the current is always changing it creates a magnetic field in the primary that overlaps the secondary and the secondary coils get a current induced in them from the VARYING magnetic field from the primary. this current in the secondary is also alternating current so when its connected to a simple incandescent or florescent bulb it does create continuous seeming light but the blinks are so fast we cant see them the brightness of the bulb is actually varying but so fast that our eyes don't see it. does that help with the question the light will stay on continuous but it will vary so fast that you cant see it. good question
Umm, is the power source AC or DC? You are right, transformers usually use AC. Is it not using AC in this example? You didn't say. If it's using AC, the light bulb will stay on. The current actually switches on and off, but so fast you don't see it. Well, normally, for household 60Hz AC power. But who knows with this mystery power source. It could be 1Hz AC. If it's using DC, then it will come on for a short time (a few seconds? I don't know). Yes, current is continually flowing through the primary circuit, but after a while no current will be flowing through the secondary circuit where the light bulb is connected. It takes change in current in the primary circuit to induce a current in the secondary circuit.
Every light bulb in your house is connected to the secondary circuit of a transformer, which is either in the street on on a pole outside your house. so yes, the bulb will stay on. AC current is continuously flowing, that is why it is AC, alternating current. It reverses direction 60 times a second. .

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