How Everything Works
How Everything Works How Everything Works

Question 235

Can you explain power surges?
Sometimes lightning strikes a power line and deposits a large amount of charge on it. This charge has considerable electrostatic potential energy so its voltage is very large (a large positive voltage if the lightning carried positive charge, a large negative voltage if the lightning carried negative charge). A the charge flows outward along the wires, it raises the local voltages of the wires. This sudden, brief increase in the local voltages is what you mean by a power surge. Many devices (e.g. computers and televisions) can be damaged by such a surge in voltage. Even a light bulb can be damaged because the extra voltage pushes too much current through the filament and can burn it out.

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