Current Basics
Electric current, charge flow, complete paths, and the conditions required for a circuit
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Show Me The Physics
D) Conditions for passing current
Voltage, Resistance and Current
1) complete circuit
2) potential difference (voltage) supplied by some source ex. Battery, generator
3) conductor (wires)
I. Important Circuit Terms
A) Current (I) - measure of charge flow
Click on this link if your school blocks flash CurrentVideoQT.htm
Scientific Advisors: Dr. Saul Dushman; Dr. Roman
Smoluchowski; Dr. David Harker Full Size Current Video
q = charge (C) t = time (sec)
= (C)/(sec) UNIT OR Amperes
Ex) If 10. coulombs of charge are transferred through an electric circuit in 5.0 seconds, then the current in the circuit is
I = 10. C/5.0 sec
I = 2.0 Amps
1 Coulomb = 6.25 x 1018 electrons (A bundle of Electrons) p. 1 Reference
Ex) A wire carries a current of 2.0 amperes. How many electrons pass a given point in this wire in 1.0 sec?
Cross Multiply And Divide
#e- = 1.3 x 1019 (2 sig. figs.)
AP Physics Giancoli - p. 515) 8
V = IR
9.0 V = I[1.6 ohm]
I = 5.6 Amps I = q/t q = It q = 5.6A(60 sec) = 330 C divide by 1.6 x 10-19C
= 2.1 x 1021 elect.
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Check Your Understanding
5 quick questions — pick an answer to see if you’re right.
1. Electric current (I) is best defined as:
2. 12 coulombs of charge pass through a circuit in 4.0 seconds. What is the current?
3. A wire carries 1.6 A for 1.0 s. How many electrons pass a point? (e = 1.6 × 10⁻¹⁹ C)
4. Which is NOT one of the conditions needed for current to flow?
5. A bulb is connected to a fresh battery, but the switch is open. Why is the bulb off?