1. Voltage, V Voltage tells us how hard a positive charge is pushed between two different points. Something, such as a battery, is needed to create a voltage. Current, I Current tells us the amount of charge flowing through something (similar to gallons per minute). Current must have a path through which to flow. Wires provide a path for current flow (and offer no no resistance to the flow).

2. What Are These? Battery Wires Switch Light Bulb

3. New Symbols Battery Switch

4. Old Circuit Drawing

5. New Circuit Drawing

6. How Much Current Flows? Switch is open. Zero. This is an “open circuit.”

7. How Much Current Flows? Switch is closed. TOO MUCH!!! This is a “short circuit.”

8. How Much Current Flows? Light bulb has resistance to flow of charge. Amount of resistance is some number R.

9. Resistor Symbol R

10. Electrically: Light Bulb = Resistor Current, I = V / R

11. LED: A Different Kind of Light Bulb LED = Light Emitting Diode Current can only flow in one direction (in direction of arrow). Light only emitted when current flows. A lot of current may flow if a large large voltage is across an LED.

12. Dangerous LED Circuit When switch is closed, too much current may flow! Almost behaves as a short circuit. Need to modify circuit to limit current…

13. Good LED Circuit When switch is open, light is off. When switch is closed, light is on. Resistor limits current flow.

14. Good LED Circuit 5V0 GND