chapter 4 n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Chapter 4 PowerPoint Presentation
Download Presentation
Chapter 4

Loading in 2 Seconds...

play fullscreen
1 / 21

Chapter 4 - PowerPoint PPT Presentation


  • 71 Views
  • Uploaded on

Chapter 4 . Resistance. Resistance Opposition to electron flow in a circuit. Expressed by the symbol R. Measured in ohms. Abbreviated with the Greek symbol . Varies from material to material. Silver is best. Copper is most common. Gold doesn’t tarnish. Affected by temperature.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Chapter 4' - psyche


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
chapter 4

Chapter 4

Resistance

slide2
Resistance
    • Opposition to electron flow in a circuit.
      • Expressed by the symbol R.
      • Measured in ohms.
      • Abbreviated with the Greek symbol .
      • Varies from material to material.
        • Silver is best.
        • Copper is most common.
        • Gold doesn’t tarnish.
        • Affected by temperature.
        • Affected by the size (diameter) of the conductor.
slide3
Resistivity
    • The resistance of a material to current flow.
      • Resistivity is different for different materials.
      • Even good conductors have different levels of resistivity.
    • In electric circuit, the larger the diameter of the wire, the lower the electrical resistance to current flow,
    • One ohm is the resistance of a circuit, or circuit element, that permits a steady current flow of one amp when one volt is applied to the circuit.
slide4
Conductance
    • The ability of a material to pass electrons.
      • Unit known as Mho (ohm backwards).
      • Abbreviated with the inverted Greek symbol Ω.
slide5
Resistors
    • Components manufactured to possess a specific value of resistance to the flow of current.
    • Come in two classifications:
      • Fixed value
      • Variable
    • Variety of shapes and sizes to meet specific circuit, space, and operating requirements.
slide6
Tolerance
    • The amount that the resistor may vary and still be acceptable.
    • The larger the tolerance, the cheaper it is to manufacture.
    • Resistors are available with tolerances of ±20%, 10%, 5%, 2%, and 1%.
slide7
Molded carbon resistor
    • The most commonly used.
    • Inexpensive
    • Manufactured in standard resistor values.
  • Wire wound
    • Used in high-current circuits.
    • Resistance varies from a fraction of an ohm to several thousand ohms.
slide8
Film resistors
    • Becoming increasingly popular.
    • Three types: carbon film, metal film, and tin oxide film.
  • Surface mount resistors
    • Ideal for small circuit applications.
    • Available in both thick and thin films.
slide9
Variable resistors*
    • Allow the resistance to vary.
    • Vary linearly or logarithmically.
    • Called a potentiometer when used to control voltage.
    • Called a rheostat when used to control current.
slide10
Resistor identification
    • Alphanumeric
    • EIA (Electronic Industries Association) Color Code
    • The color bands are read from left to right,
resistors color codes
Resistors – Color Codes

Reproduced by permission of Tony van Roon, 2002http://www.uoguelph.ca/~antoon

slide12

1st Band 2nd Band 3rd Band 4th Band

1st Digit 2nd Digit Number of Zero’s Tolerance

BLACK 0 0 N/A N/A

BROWN 1 1 0 1%

RED 2 2 00 2%

ORANGE 3 3 000 N/A

YELLOW 4 4 0,000 N/A

GREEN 5 5 00,000 0.5%

BLUE 6 6 000,000 0.25%

VIOLET 7 7 N/A 0.10%

GRAY 8 8 N/A 0.05%

GOLD N/A N/A X.1 5%

SILVER N/A N/A X.01 10%

NO COLOR N/A N/A N/A 20%

EIA Color Code

slide13
Example of EIA color code:*
    • Orange = 3
    • White = 9
    • Red = 2 zeros
    • Gold = 5%

= 3900 ohms or,

  • Resistor is a 3.9K Ohm 5% tolerance fixed resistor.
slide14
Resistors in Circuits
    • Resistors are typically configured in a circuit in one of three different ways:
      • Series circuit configuration.
      • Parallel circuit configuration.
      • Compound circuit configuration.
lab 1 4
Lab 1-4
  • Go to the classroom website and complete the Labs for Resistance.
    • You can find Lab 1-4-A and 1-4-B in the Handouts tab in the dashboard on the classroom website.
    • Type your answers in Microsoft Word and upload to the classroom website when completed.
resistors in a series circuit
Resistors in a Series Circuit
  • A series circuit contains tow or more resistors and provides on path for current to flow.
  • Current runs from the negative side to the positive side,
  • The more resistors in the circuit, the more resistance to current flow,
  • The total Resistance in a series circuit is the sum of the individual resistors in the circuit,
slide17
Series circuit comprised of resistors:
  • To calculate out the total resistance we use the formula RT = R1 + R2 + R3 + etc.
  • The total resistance for the above figure is:
    • 60 OHMS
resistors in parallel
Resistors in Parallel
  • A parallel circuit contains two or more resistors and provides two or more paths for current to flow,
  • Each current path is called a “branch”,
  • The more “branches”, or paths, the less opposition there is to current flow, (less resistance),
  • When a resistor is added in parallel to a circuit, the total resistance in the circuit decreases.
slide19
Parallel circuit comprised of resistors:
  • Formula to calculate the total resistance
  • The total resistance for the above figure is:
    • 5.45 OHMS
slide20
Compound circuit comprised of resistors:
  • To calculate the total resistance we use both the series and parallel formulas.
  • Total resistance for the above figure is:
    • 66.7 OHMS
slide21
In Summary:
    • Resistance
      • Resistors
      • Resistivity
      • Conductivity
    • Resistor identification
      • Fixed
      • Variable
    • Circuit configurations
      • Series
      • Parallel
      • Compound