1. Types of Simple Circuits Series circuit All in a row 1 path for electricity 1 light goes out and the circuit is broken Parallel circuit Many paths for electricity 1 light goes out and the others stay on

2. Series Circuits In series circuits, current can only take one path. The amount of current is the same at all points in a series circuit.

3. Series Circuits The amount of current is the same at all points in a series circuit. How can we find out what that current is? 1.We can add the resistances to find the total equivalent resistance. 2.Then use Ohm’s law & the total voltage to find the current.

4. Total resistance in a series circuit Light bulbs, resistors, motors, and heaters usually have much greater resistance than wires and batteries. Each resistance in a series circuit adds to the total resistance of the circuit. What would be the current in this circuit? Hint: Use Ohm’s Law.

5. Practice Problem Find the unknown voltages for each resistor:

6. Series Circuits: ‘Series is simple’ Current’s constant. Ohm’s law will apply to the totals, AND at each resistor. Lose one resistor, all ‘die’. For example, Christmas lights.

7. Parallel Circuits In parallel circuits the current can take more than one path. Because there are multiple branches, the current is not the same at all points in a parallel circuit.

9. Advantages of parallel circuits Parallel circuits have two big advantages over series circuits: 1. Each device in the circuit sees the full battery voltage. 2. Each device in the circuit may be turned off independently without stopping the current flowing to other devices in the circuit. For example: Household wiring

10. Short circuit A short circuit is a parallel path in a circuit with zero or very low resistance. Short circuits can be made accidentally by connecting a wire between two other wires at different voltages. Short circuits are dangerous because they can draw huge amounts of current. Electrons follow the path of least resistance! Give them a short-cut & they’ll take it!

11. Parallel Circuits: Voltage’s constant. Ohm’s law still applies to the totals, AND at each resistor. Lose one resistor, and the rest will keep working. For example, house wiring.

12. Quick review before you go… 1.Put your name on the half sheet you’ve been given. 2.Number it #1-4. 3.Answer the following questions. 4.Hand it to me as you exit.

15. The circuit is no longer complete, therefore current can not flow The voltage decreases because the current is decreased and the resistance increases.

16. The current remains the same. The total resistance drops in a parallel circuit as more bulbs are added The current increases.