Physics 12

Mr. Jean

April 17th, 2014

The plan:

• Complex Circuits

• How Circuits are graded

Complex Circuits:

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.