Measuring current and Household Wiring

Magnetic fields exert force on a current-carrying wire; we can use these forces to measure the current.
A galvanometer is a simple device to measure current via deflection of a current-carrying wire in a magnetic field.
By splitting the current through an ammeter into several pieces via shunt resistors, one can extend its range.
Typical houses contain several circuits, all connected in parallel to the external power supply. Each circuit is rated to carry at most a certain current (typically 10 to 30 amps)
Each circuit contains a circuit breaker, or a fuse, to prevent larger currents from flowing
Three-prong wires contain a special ground wire which carries any stray current through an appliance away from human touch.

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