Answer to Question #350636 in Electric Circuits for Rivoningo

Question

Resistor consist of R1=4, R2= 4.5 R3= 12

Resistor R3 connected in parallel with R2 .

1 )draw a the circuit diagram

2 )calculate the voltage across R3 if the applied voltage is 12V .

3 ) calculate the current passing R1 and R 3

Answer 1

Solution:

Some notes: in the given of problem there is not full information about how R1 connected to the circuit. That's why I will try to find solutions as example.

1) See attach image for some possibility of circuit diagrams.

2) We will find voltage via R3 according to 1 diagram.

Let's find total resistance of circuit:

$R_{23}=\frac{R_2R_3}{R_2+R_3}=\frac{4.5\times12}{12+4.5}=3.3;$

$R=R_{23}+R_1=3.3+4=7.3;$

So, total current of circuit:

$I=\frac{U}{R}=\frac{12V}{7.3}\Omega=1.64A;$

From Krich's rule:

$I_2R_2=I_3R_3; \space and \space I_3+I_2=I;$

$I_3=\frac{R_2}{R_2+R_3}\times I=\frac{4.5}{4.5+12}\times 1.64=0.45A;$

$U_3=I_3R_3=0.45A\times12\Omega=5.37V.$

3) For 1 diagram:

$I_1=I=1.64A;$

$I_3=0.45A.$