**72. The circuit shown in the drawing is constructed with six identical resistors and an ideal battery. When the resistor R4 is removed from the circuit, the current in the battery decreases by 1.9 A. Determine the resistance of each resistor.

 

w1030

 

First we need the total resistance.  So starting away from power source we have R1, R3, and R5 all in series so we can add them and Reff1 = 3R and our circuit looks like

Now add the 3R and R in parallel and we get

 

 

And the circuit now looks like

Now we have three resistors in series so the total resistance is

 

 

So the current is

 

Now if only R4 is removed the circuit looks like this

In this case we have 5 resistors all value R in series, so

 

And current now is

 

Finally problem tells us that

 

Now solve for R

 

 

 

 

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This page last updated on June 18, 2018