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Objectives:
        - Students will learn about resistors and electrical friction

        - Students will be able to solve for resistance

Real Life Applications:
   - Ovens
   - Microwaves
   - Hair Dryers
   - Freezers
   - Most electrical appliances

Resistors are arranged in to either a parallel or series circuit
   Parallel- The current can have more than one path
   Series-  All resistors connected in one path
   Hybrid- Uses both series and parallel

 Resistors- are electrical components that are used to control the voltage or current in a circuit.  The less conductive the material is the more resistance it has.

1st Color Band- The 1st color just represents the first number of the resistor.  For example in the picture it is brown so the first number would be 1.

2nd Color Band- The 2nd color also just represents a number.  In the picture the color is black so the 2nd number would be zero.

Multiplier Color Band- This color band tells you how many zeros to add to the resistance.  The color on this band is red so the number of zeros you would add would be 2.  So the final resistance would be 1000 ohms.

Tolerance Color Band- This color band tells you the percentage of accuracy the resistor has.  Because this resistor has a gold band it is 5%. (Tolerances Gold= 5% Silver=10% None=20% )

Formula-
    To find the total resistance of a circuit first you must find the resistance of each resistor.  Once you have done that you have to determine whether it is in a series or parallel.  Ohms is the unit for resistance.

  Series- Just add all of the resistors together for total resistance

   Parallel- To find total resistance add the inverses of the resistors together and then take the inverse of the final answer

   Hybrid- Solve for both series and parallel separately then add them together
 

Examples-

1.   Solve for the resistor

      Answer:
                Black- 0
                Red- 2
                Green- 5
        Resistance- 200,000 ohms

2.  (Series Circuit)
 

      Answer:
            Black- 0                     Red- 2
            Red- 2                       Red- 2
            Yellow- 4                    Brown- 1
   Resistance- 20,000 ohms        Resistance- 220 ohms
                       Total Resistance- 20,220 ohms

3.


(Parallel Circuit)

Answer: Green- 5                    Violet- 7                      Green- 5
         Blue- 6                      White- 9                      Black- 0
         Black- 0                    Orange- 3                      Brown- 1
    Resistance- 56 ohms       Resistance- 79,000 ohms     Resistance- 500 ohms

Total Resistance 56^-1 + 79000^-1 + 500^-1
                       = .0199^-1
                      = 50.328 ohms

4.

(Hybrid Circuit)

Answer: Series-  White- 9                     Red- 2
                   Red- 2                       Brown- 1
                   Black- 0                      Brown- 1
                Resistance- 92 ohms        Resistance- 210 ohms

          Parallel- Brown- 1                      Yellow- 4
                    Black- 0                      Blue- 6
                    Black- 0                      Brown- 1
                Resistance- 10 ohms         Resistance- 460 ohms

Total Resistance 92 + 210 + (10^-1 + 460^-1)^-1
                      = 302 + (.102)^-1
                        = 311.79 ohms
 

Links:
 Voltage, Resistance and Current
 Physics Classroom
 Example Problems