Use a Multimeter to Measure Resistance in a Circuit For this project, you will need an extension…

Use a Multimeter to Measure Resistance in a Circuit

For this project, you will need an extension cord and a
lamp, a good battery, and a multimeter to measure the resistance in two
circuits.

1. Turn the function selector on the multimeter to the
lowest setting on the resistance (ohms) scale. Touch the probes together and
adjust the meter needle to zero using the ohms adjust control.

2. Place the extension cord on a table with both the plug
end and the outlet end pointing toward you. Do not plug the cord into an
outlet. Resistance readings are always taken with the power off.

3. Put
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Use a Multimeter to Measure Resistance in a Circuit

For this project, you will need an extension cord and a
lamp, a good battery, and a multimeter to measure the resistance in two
circuits.

1. Turn the function selector on the multimeter to the
lowest setting on the resistance (ohms) scale. Touch the probes together and
adjust the meter needle to zero using the ohms adjust control.

2. Place the extension cord on a table with both the plug
end and the outlet end pointing toward you. Do not plug the cord into an
outlet. Resistance readings are always taken with the power off.

3. Put the probes into the outlet end of the cord, one on each
side as if you were plugging the meter into the cord.

4. Read the resistance on the top dial of the meter. Why is
the resistance so high?

5. Try changing the function selector to the highest
resistance scale. Does the needle move? Why or why not?

 6. Change the function selector back to the lowest
resistance scale.

7. Place a piece of metal (a paper clip or a small
screwdriver blade) fi rmly across the two blades of the extension cord plug.

8. Read the meter on the resistance scale. Why did the resistance
drop?

9. What is the resistance for the cord you are measuring?
Note it for comparison with the lamp you test next.

10. Turn on the lamp you will measure for resistance and
unplug it while it is still turned on.

11. Touch the probes to the blades of the lamp plug. What is
the resistance? Is it more or less than the cord? Why do you think that is?

 12. Turn the lamp switch off. What happens to the
resistance reading? Why?

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