Physics 12 Circuits 6 – Basic Complex Circuits Mr. Jean

The plan: Complex Circuits How Circuits are graded

Complex Circuits:

Hint Ideas: Get the Circuits into groupings. Grouping depend on the way the different loads are acting on each other.

Thus for this example: We have to first deal with the R2 & R3 group. This group is a parallel circuit. Then once this is complete we can move onto the next grouping. Let’s label R2 & R3 as group A.

Now we can see that once we deal with group A (which is the parallel circuit) we can then work with the entire circuit. Since the rest of the circuit is a series circuit. So solve for equivalent resistance through group A (using the parallel circuit technique) and the we can attack this circuit like we would before.

By solving the group A’s resistance we can now find the entire circuits equivalent resistance by applying the series formulas.

Using Ohm’s law and the properties of circuits we can then find the current in the system.

Once we have the current through the entire system we can then solve for the voltages across R1 & Group A.

We can then look at the current through R2 and R3 of resistors. Again we use Ohm’s Law. V = IR

Let’s make up a circuit: We have a “AA” battery with 1.5volts. Grant (R1) is holding the battery under water while holding two wires. On one wire we have a LED, on the other wire we have a very cheap heater and we have Davie with a SPST switch which is connected to the other end of the battery.

Circuit Diagram: 2 Pts Circuit is properly drawn Circuit has labels

Calculations for Amps: 5pts Correct formula for current Correct Calculation for current Correct resistance for Light Correct resistance for heater Correct units for each

EQ Resistance: 3pts Correct formula Correct units Correct calculations

Complex Circuit Create diagram Solve for current and voltage through each. Resistors R1, R2, R3 have the following resistance 2ohm, 6ohm, 12ohm and are connected to a 12 volt battery source. R1 & R2 are in parallel with each other but in series with R3. –Solve for the voltage drop and current through each.