Circuit Symbols

A V

CURRENT

Current Definition: The number of electrons flowing through a point in a circuit in one second Unit: Current is measured in amperes (A) Measuring Device: Current is measured by an ammeter Naming: Named after André-Marie Ampère, a French physicist

The Coulomb Because the number of electrons travelling through a circuit is astronomically high, we need a different unit of measurement x is one coulomb of charge Therefore, 1 A is one coulomb per second Charles-Augustin de Coulomb was a French physicist 1A = electrons passing in one second x 10 18

Does the addition of light bulbs in series change the current?

A A A 1 A

A A A Series Circuit A t =A 1 =A 2 =A 3 …

Does the addition of light bulbs in parallel change the current?

A 1 A3 A A A A A

A 1 A3 A A A A A Parallel Circuit A t =A 1 +A 2 +A 3 …

Some Math Remember: Current is the number of electrons that pass a point in a circuit every second. QuantitySymbol CurrentI ChargeQ Timet Q t I = Q I t

1.How many amps are there in a circuit where 10C of charge pass by in 6 seconds? 2.How many coulombs of charge passed by a circuit if a 10A circuit was left on for 4 minutes? 3.How long does it take 18 coulombs of charge to pass through a 200mA circuit?

Current ratings of common loads Electrical Device (Load)Electric Current (A) Wristwatch Calculator0.002 Electric clock0.16 Light bulb (100W)0.833 Television4.1 Electric drill4.5 Vacuum cleaner6.5 Stove element6.8 Oven element11.4 Toaster13.6 Water heater element27.3 Car started motor (V-8)500.0

Current Kills Even a very small amount of current is deadly Perception level: 0.001AMuscles Tingle: 0.002AMaximum safe level: 0.005A Muscles convulse: 0.016A Breathing affected Severe burns: 0.200A no breathing Current needed for 100W bulb: 0.833A Heart stops: 0.050A