Circuit Analysis: Why Birds Survive on Power Lines
Kirchhoff, Thévenin, phasors and three-phase power: the core rules that predict how any circuit behaves, with a few surprises.
Circuit Analysis · 50 questions
Try 3 questions
1. A battery that powered one resistor now powers two identical resistors in series. What happens to the total power drawn?
- It halves
- It stays the same
- It doubles
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Answer: It halves
Resistance doubles, so current halves at the same voltage, and power P = V·I halves too.
2. Kirchhoff's current law, that currents into a node sum to zero, expresses the conservation of what?
- Magnetic flux
- Electrical energy
- Electric charge
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Answer: Electric charge
Charge cannot pile up at a node, so whatever flows in must flow out.
3. Why can a bird perch safely on a single high-voltage power line?
- Its body bridges almost no voltage difference
- Current avoids flowing through living tissue
- Its feet insulate it from the wire
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Answer: Its body bridges almost no voltage difference
Both feet sit at nearly the same potential, so almost no voltage drives current through the bird; touching a second wire would be deadly.
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