D) Conditions for passing current

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Voltage, Resistance and Current

 

 

1) complete circuit

 

2) potential difference (voltage) supplied by some source

ex. Battery, generator

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3) conductor (wires)

 

 

 

I. Important Circuit Terms

 

A) Current (I) - measure of charge flow

 

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Full Size Current Video

 

 

 

 

I = q/t 

 

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

 

 

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

 

I =  (#e-)(1.6 x 10-19 C)
t

 

 

Ex) A wire carries a current of 2.0 amperes.

How many electrons pass a given point in this wire in 1.0 sec?

Ex) A wire carries a current of 2.0 amperes. How many electrons pass a given point in this wire in 1.0 sec?

 

I =  (#e-)(1.6 x 10-19C)
t

 

 

2.0 A =   (#e-)(1.6 x 10-19 C)
1.0 sec

 

Cross Multiply And Divide

 

2.0 A   = (#e-)
(1.6 x 10-19  C)

 

#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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