Home Chapter 4 Identifying and Measuring Resistances with your multimeter
Identifying and Measuring Resistances with your multimeter
Chapter 4

 

  1. Grab any resistor from your kit.
  2. Look closely at the resistor and notice that three of the colored bands are closer than the other colored band. The other colored band will be silver, gold, or red.
  3. Hold the silver, gold, or red color band that is farthest from the others in your right hand. The silver, gold, or red band that is now closest to your right hand is called the tolerance band of the resistor. This color band tells you how far away this resistor may be, from the stated value. For example if you had a resistor of 1KΩ and you had a gold band it would mean the resistor would vary up or down in value by 10% so you resistor could have a value of 900Ω or 1100 Ω.
  4. The stated value is what the other three-color bands say the resistor value is. For example, brown, black, and orange would mean the resistor is 10kΩ, or 10,000Ω. Refer back to the color code chart.

 


  1. Look at the colored bands on the resistor you have selected from your kit and write the colors in the spaces provided. 1st color _____ 2nd color ______3rd color _______ 4th color (band farthest from the others held in your right hand and silver, gold, or red color. ___________
  2. Go to the chart above and match the colors to the numbers. The first band is the first digit of your resistor value, the second band is the second digit of your resistor value, and the third band is the number of zeros added to these numbers.
  3. This is the resistor value. Note: If you wrote your value out as 1000Ω then you can shorten this to 1kΩ, as K is short for 1000.
  4. One more example: if you had a resistor that reads brown, red, orange, and gold in the tolerance band. You would have a 12kΩ resistor that could vary above and below 12kΩ by 5%.

In the next exercise you will be using the resistor chart to measure the resistance first using the colors on the resistor in association to the color key above and then confirming this color chart reading with a measurement of resistance you take with your multimeter.

You will also be using the breadboard without power as a place to measure the resistances with your meter.

Parts Required:

5-resistors of different values
A breadboard or the white prototyping area including from the Arduino breadboard or Board of EDU.

A suitable digital multimeter with Ohms measurement capability

 

Start with the probe set to the highest value of resistance and work your way down to get the most accurate reading.

  1. Take five different resistors from your kit and, one by one, place them in the on the breadboard as shown below. Notice how they bridge the small valley that exists between the two sides of your white breadboard.

    Breadboard with five different values of resistors.

     
  1. Make sure you have the resistors oriented so that you can easily get your multimeter probe tips to make a solid electrical connection.
  2. First, use the color chart to read and compute the value of the resistor and the tolerance and write them down below in the blank spaces to the left notated A, B, C etc.
  3. Now use your multimeter to read the same resistor you calculated using the colors and write the value in the column to the right of the column you wrote the value in. Compare your multimeter value to the color chart value.

 

Test the resistors one by one with your multimeter. 3D model by Todd Swepston

 

Color chart reading Multimeter reading

Resistor 1 ______________ _______________
Resistor 2 ______________ _______________
Resistor 3 ______________ _______________
Resistor 4 ______________ _______________
Resistor 5 ______________ _______________

Were there different values between what the color codes stated and what your multimeter measured, and if so, why?
___________________________________________________________________

 Measuring Resistances of Random Objects

Now, for the fun of it, try measuring a variety of different objects, such as plastic, metal doorknobs, metal frames, ceramics with and without glazes, etc.

Try measuring your own bodies resistance and see how it compares to the resistances of other people.

It is also fun to hold onto one lead of the multimeter with one hand and give one lead to a friend to hold onto and hold hands to see what your combined resistance is. You have just created a series circuit. This is in fact the same for resistors. You can add one resistor to another end-to-end and the total resistance will be the two added up.

You may have to lick your fingers first to provide a good connection to the multimeter probes but be sure to wash your hands first if you have touched the BS2 and encountered any lead that may be on your fingers.

For measuring your own resistance set your probe to the highest setting as well and play with the probe settings within the realm of resistance as you measure various objects.