miércoles, 9 de septiembre de 2015

Ley de Ohm I

Ohm's Law,
Example One

The circuit below is called a Wheatstone bridge. It is used for measuring resistance. Show that when the current through the galvanometer G is zero, then R1 = R2(R3/R4). Thus, if we know R2 and the ratio (R3/R4), we can obtain the resistance R1.
IG = 0 means points C and D are at the same potential and
that I1 = I2, I3 = I4.
By Ohm’s law VAC = I1R1, VAD = I3R3, VCB = I2R2, VDB = I4R4.
As VAC = VAD and VCB = VDB, then I1R1= I3R3,
I2R2= I4R4.
As I1 = I2 and I3 = I4, then doing I1R1/ I2R2=I3R3/I4R4 we get R1= R2(R3/R4)

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