E8: Voltmeters, ammeters, and power supplies Materials: ammeter, voltmeter, low-voltage power supply, bulbs, batteries, wires, switch, enthusiasm… Initial definitions and givens: Ampere (aka amp): a measure of the strength of an electrical current. In a 1-ampere current 6x10 18 electrons pass each second through a cross section of whatever the current is flowing through (wire, bulb, battery, whatever). One ampere is about the current that flows through a standard 100-watt light bulb. Volt: a measure of the ability of a battery (or other power supply) to drive current through a circuit. Can be thought of as “electric pressure”. Ohm: a measure of the resistance of a bulb or other part of a circuit. A 1-volt battery would drive a current of 1 ampere in a circuit whose resistance is 1 ohm. Ammeter: a device that measures current. An ammeter measures the current passing through it, so it is wired in series. An ammeter has very low resistance. Voltmeter:
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