In, general, I dont understand double and single voltage notations. How do I find Vab, and Vcb? Steps would really help.
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\$\begingroup\$ I don't see any 'double voltage notations' (and I have no idea what that could mean). But unless I miss something your circuit is very simple. Can you calculate the total voltage over the resistors? The totall resistance? The current? And from that, the voltage over each reistor? Alternatively, you could googe the formula for a voltage divider, but that would not lern you much. \$\endgroup\$– Wouter van OoijenCommented May 21, 2016 at 13:44
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\$\begingroup\$ How do I calculate Vab then? Can you explain the process? \$\endgroup\$– darkhorseCommented May 21, 2016 at 13:47
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1\$\begingroup\$ you have two unknowns. You know the sum of the two voltages. You know the ratio between them (assuming you have learned Ohm's Law). That gives you two simultaneous linear equations. So, one way is to solve them. One hint : watch your signs. \$\endgroup\$– user16324Commented May 21, 2016 at 13:52
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1\$\begingroup\$ \$V_{ab} = V_a - V_b\$ and \$V_{cb} = V_c - V_b\$ \$\endgroup\$– CurdCommented Mar 8, 2017 at 1:12
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2 Answers
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- Define Vac numerically - that should be really obvious
- Find the current flowing through both resistors (ohms law)
- Multiply that current by R2 to get Vab
- Multiply the same current by R1 to get Vbc
answered May 21, 2016 at 13:47
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Option#1: If you know superposition you could use that. For those that don't know superposition, you analyze the circuit with only one voltage source at a time and find the currents magnitude and direction, the unused source is shorted out. The final current is the sum of both currents (making sure to account for direction as necessary as opposing sources can partially cancel each other out). Using the resulting current you could solve for each voltage using ohms law.
Option#2: If you know mesh analysis, draw the circuit up as a mesh and solve for the loop equation. In this case you only have one loop so that makes it easier from the maths perspective.
The double and single notation is simply a way of expressing what you are referencing. In single notation you are referencing the node with respect to ground (ie Va is node 'a' to ground). In double notation you are specifying a specific location for a reference (ie Vab is the voltage at 'a' with respect to the voltage at 'b', which in your example is the voltage across R2. Vbc is the voltage across R1, and Vac is the combined voltage across both).
