Current and Ohm's Law
Study Guide for Chapter 27
Outline
1. Electric Current
Electric current
magnitude
is the flow of electric charge.
The
of the current is the charge per
unit time that flows through the conductor:
M œ
M œ
U
.U
>
.>
?
or
Current is measured in
(A, often pronounced “amps”), where
A
C s.
amperes
" œ" Î
The
of a current is the direction in which the positive charges are flowing.
If
direction
negative charges are flowing instead, the current is in the
opposite
direction of charge flow.
If you know the current in a conductor, you can find out how much charge passes through the
conductor over a period of time using the formula
U œ M >
U œ
M.>
?
or
(
Problems:
1, 7, 9
2. Resistance and Ohm's Law
A
is any object that charge has difficulty flowing through.
Charge will only move
resistor
through a resistor if it is
pushed
through by a potential difference.
The main result of this section is
, which relates the potential difference across a
Ohm's law
resistor with the current that flows through:
?
Z œ MV
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 Spring '10
 Turner
 Potential difference, ohm, Electric charge, Electrical resistance

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