How do you calculate the total resistance of a parallel circuit?

1 Answer
Biology_geek · Media Owl · Jackie Shlecter
Apr 14, 2014

Use the resistance formula:

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Example:

You have 4 resistors all connected in parallel. R1 and R2 each have a resistance of 4 ohms, R3 and R4 each have a resistance of 8 ohms. What is the total resistance?

#1/"Rp"# = #1/"R1"# + #1/"R2"# + #1/"R3"# + #1/"R4"#

#1/"Rp"# = #1/4# + #1/4# + #1/8# + #1/8#

(Find a common denominator)

#1/"Rp"# = #2/8# + #2/8# + #1/8# + #1/8#

#1/"Rp"# = #6/8#

(Rp is the reciprocal of this)

Rp = #8/6# = 1.33 ohms

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