# Calculating source voltage in circuit

Given the circuit I have to find the source voltage S and unknown resistance R3. It is stated that the power dissipated in R6 = 3 ohm is 0.75W. How should I attempt to solve the source voltage where there are two unknown variables?

simulate this circuit – Schematic created using CircuitLab

Edit: Combining series resistors and trying mesh analysis:
14I1-2I2 = S ...(i)
-2I1+18I2-4I3 = 0 ...(ii)
-4I2+(7+R)I3=0 ...(iii)
P=(I^2)*R , So, I3=0.5A

• Show what you have attempted so far. – Solar Mike Jun 13 '19 at 10:09
• Start by looking at the circuit, can it be simplified? I see that R1 and R8 are in series and can be combined.When the circuit is simplified write the network equations to find the solution. – Bimpelrekkie Jun 13 '19 at 10:14
• R3 and R6 are in series. What do you know about current in series circuits? – JRE Jun 13 '19 at 10:28
• Can you calculate the current through a resistor given the resistor value and the dissipated power? – JRE Jun 13 '19 at 10:29
• Have you heard of source transformation? – Andy aka Jun 13 '19 at 10:33