Circuit Elements

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PHYS-1500 PHYSICAL MODELING FALL 2006

Circuit Elements

A resistor is familiar to most students of high school physics. Its symbol is:

The potential difference (or voltage) across a resistor is proportional to the current passing through it.

V

= –

iR

, where

i

is the current, and

R

is the resistance. The minus sign means that the potential decreases in the direction that the current flows.

A capacitor is symbolized by:

The potential difference (or voltage) across a capacitor is proportional to the charge on it.

V

= –

q/C

, where

q

is the charge, and

C

is the capacitance. The minus sign means that the potential decreases in passing from the positively charged plate to the negatively charged plate.

An inductor is symbolized by:

The potential difference (or voltage) across an inductor is proportional to the rate of change of current through it.

V

 

L di dt

, where

i

is the current, and

L

is the inductance. The minus sign means that the potential decreases in the direction of increasing current.

A source of emf is often symbolized by:

The longer parallel line indicates the side that is at higher potential (the positive side).

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