A charge of #8 C# passes through a circuit every #2 s#. If the circuit can generate #3 W# of power, what is the circuit's resistance?

1 Answer
Dec 19, 2016

I found: #0.2Omega#

Explanation:

You know that current #I# is the rate of passing of charge #Q# through a section of a conductor with time #t# or:

#I=Q/t#

in your case:
#I=8/2=4A#

Power #P# is the rate of transformation of energy with time that, in case of electrical circuits, can be written (using also Ohm's Law: #V=RI#):

#P=VI=V^2/R=I^2R#

using the last one:

#P=I^2R# and rearranging:

#R=P/I^2=3/4^2=3/16=0.1875~~0.2Omega#