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Book - Chapter 3

In this activity, you will be using the multimeter to do a continuity test on the breadboard by touching the probes to some wire and then to some plastic.

1. Put your multimeter on the lowest setting of Ohms (Ω) possible. This is 200 ohms on many multimeters. Some meters have a continuity tester that makes sound and if this is the case turn your meter to that setting in stead of the lowest value of Ohms.

We have not yet studied Ohms or Ohms law, but we will in chapter 4. For the purposes of today’s lesson, focus on using the Ohms setting on your multimeter to measure continuity.

 Turn your meter to the OHM's setting

 Ohms are a measure of how much resistance a material presents to the passage of electrons.

2) Notice that when the multimeter probe leads are not touching, your LCD readout gives you a number like one in the left side of the LCD readout.

3) Notice that when you touch the black probe to the red probe tip, at first the meter reads a number that bounces around and then you get a reading like .9, .8 or .6 This means there is an electrical connection between the two points or that you have what is called a dead-short. It is an indication that indeed you have a good electrical connection between those points.

4) Now put a jumper wire in the breadboard as shown below. Touch the red lead of the multimeter to one side of the wire and the black lead to the other. What reading do you get?_________________

 You must push the multimeter and wedge it between the wire and the breadboard

5) The resistance of .9, .8, .7, or .6 Ohms is the resistance of the wire and it is a very low number because the wire presents little resistance to the passage of the electrons.

This indicates that indeed an electrical connection does exist. You have just confirmed continuity in the wire or that there is a continuous or good connection.

6) Now grab a piece of wire, and with the same 200Ω setting, touch the leads to the sheathing of the wire. What kind of reading do you get? _______________

 Measuring the sheathing of the wire for continuity

Why do you get that reading? _________________

Checking for continuity is one way of determining why circuits sometimes do not work. It is often because a wire is loose or not making a proper electrical connection and this can be checked with a continuity test above. The circuit must be powered down or turned off when checking for continuity. Some multimeters have continuity checkers where the multimeter will emit a beeping sound when there is an electrical connection between two points.