The correct answer is: The voltage drop across [tex]R_5[/tex] is 45V.
Explanation:
First you need to find the total current of the circuit, which is:
According to Ohm's law:
V = I * R
I = V/R --- (1)
Where
R = Total Equivalent resistance of the circuit
V = Total Voltage = 90V
I -= Total Current
First let us find the equivalent resistance:
[tex]R = R_1 + R_2 + R_5 + \frac{R_3*R_4}{R_3+R_4} \\
R = 3 + 6 + 15 + \frac{9*18}{9+18} \\
R = 30[/tex]
Now plug in the values in (1):
(1) => I = 90/30 = 3A
Now that we have current of the circuit, we can now find the voltage drop across [tex]R_5[/tex] = 15 ohms using:
[tex]V_5 = I * R_5[/tex]
Where [tex]V_5[/tex] is the voltage drop across resistor 5;
[tex]V_5 = 3 * 15 = 45V[/tex]
