It would help if there are some options, but some common sources:
Televisions
Microwave Ovens
Cell Phones
Satellites
Wired Computers
CD players
etc.
Answer:
Stellar black holes form when the center of a very massive star collapses in upon itself.
An electric current can have no current when the switch is OPEN
Centrifugal force is not a real force.
When you move around a curve, there IS a real force pulling you
around the curve. Since your body wants to go straight, it feels as if
there's a force trying to pull you away from the curve. But there isn't.
That feeling of a force is greater when your speed around the curve
is greater, or when the curve is tighter, i.e. smaller radius.
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