1. Circuits A circuit is any directed path which includes:
A starting point (switch,valve..)‏
Power source (battery or outlet)
Set pathway defined by a medium (wire, pipes, restrictions)‏
An area of resistance or “load” (light, buzzer, heating element, fan...)‏

2. I= Q/t Q=charge Key Formulas: t=time V=IR I=current (amps)
V=voltage (volts)
R=resistance (ohms)

3. Example 1:
What is the resistance of a toaster that draws 12 amps of current from a 120V outlet?

4. Example 2:
How much current(amps) is drawn by a light bulb with a resistance of 100 ohms and 50V of electricity supplied to the circuit?

5. It is the amount of current in a “shocking” experience that can harm a human!!!
0.001amps = felt
0.005amps = pain
0.010 amps = involuntary muscle spasms
0.015 amps = loss of muscle control
0.70+ = fatality

6. Food for thought... A dry human body has a resistance of 100,000ohms.
What type of damage will a “body” experience if exposed to a standard 120V outlet?

7. Second thought... A wet body has a resistance of 1000 ohms.
What type of damage will occur if a wet body is exposed to a 120V outlet?

8. Simple circuits contain....
A voltage source
1 direction of wire
A volt reader or reactive medium or resistance medium
Switch
Examples: flashlight, room with one ceiling light, ???
Detecting problems:easy to follow path!!!

9. Series circuits contain...
A voltage source
1 direction of wires
Multiple loads
Switch
EXAMPLES: room with multiple lights which turn on with a single switch, x-mas tree lights, ???
Detecting problems: if 1 medium is broke (open) none of the circuit works.

10. Parallel circuits contain...
A voltage source
Multiple directions for current motion
Loads
Multiple switches
EXAMPLE: kitchen with multiple appliances running simultaneously.