Lab 8-3 Measuring OHMs

 

Lab Checkoff

Requirement

Completed

Measure and record the resistance of a number of cables

 

Demonstrate the proper use of a multimeter for measuring ohms

 

 

 

Objective

The objective of this lab exercise is for you to identify the resistance of a variety of different conductors:

 

Materials Required

7  Multimeter

7  Cat 5 copper cable

7  Wire

7  Section of speaker cable

7  Other cables

 

Lab Setup & Safety Tips

7  Remember that when measuring ohms you must have the power turned off, so if you’re going to measure a power supply, for example, turn off and disconnect the power.

 

ACTIVITY

Setting up the multimeter

  1. Go to the website (link on our module page) that tells you how to set up the multimeter to measure ohms.
  2. Touch the leads together to make sure you’re getting a 0 ohm reading.

 

 

Measuring different wires

  1. Get a variety of wires from me and from places around the room. Some examples might be
    1. Dead power supply
    2. IDE cable
    3. USB cable
    4. Speaker cable
    5. CAT 5 cable
  2. Following the directions in the website, measure the different types of cables and record the characteristics and ohms below.
  3. Measure the four required cables and find three others in the room.
  4. If you can’t get a reading, make a note of that and explain WHY you can’t get a reading with our multimeters.
  5. Answer the questions below.

 

Wire/Cable

Type of conductor (copper, aluminum, etc.)

Measurement

Notes

Cat5 Cable

 (be sure to measure wire for wire…if you touch one end to the blue/white, be sure you’re testing blue/white on the other end)

 

 

 

Speaker wire

 

 

 

Red wire from box

 

 

 

Yellow wire from box

 

 

 

Other______________

 

 

 

Other______________

 

 

 

Other______________

 

 

 

 

 

 

Review Questions

  1. Describe ohms.

 

 

  1. Describe how to measure ohms using a multimeter.

 

 

 

 

 

 

  1. Which wire had the highest resistance?

 

 

  1. What kind of metal was it made of?

 

  1. Which wire had the lowest resistance?

 

 

  1. What kind of metal was it made of?

 

  1. Using the information gathered in the table above, if you were creating a cable for high speed transmission, what kind of wire/metal would you want to use?

 

 

  1. Why?