For my science fair project I am measuring the resistance of nichrome wires under different conditions. I am using an Innova 3300 digital multimeter to measure the resistance. Other websites have told me to move the pointer to the Ohms section. However, there are multiple numbers in that section. What number should I use and how does changing the number affect the results?
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\$\begingroup\$ Each number represents the top-most range of resistance it can accurately measure and display. You are better off looking at youtube videos for such basic instructions in using multimeters. \$\endgroup\$– PasserbyDec 24, 2013 at 6:16
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1 Answer
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The range is set manually as opposed to auto-rangig. The number corresponds to the maximum resistance that the meter can measure. For example, if you dial 2kΩ, the meter can measure the resistance between 0 and maximum of 2kΩ. If the resistance is above the maximum, the meter will show you some non-numeric symbol, which is usually "OL".
Why are there multiple ranges? Why not just use the biggest range all the time? Smaller ranges have finer resolution. For example, at the 200kΩ range, the resolution is 100Ω. If you need to be able to tell a 220Ω resistor from a 270Ω resistor, you would need to switch to a lower range.
You can get familiar with ranges by measuring a resistor with a known value.
- If you know roughly the resistance of your nichrome wire, you can select the range based on that.
- Alternatively, you can start with the largest range, which will give you the ballpark number. The ballpark number can be zero. If the resolution is, say, 10kΩ, then a 10Ω wire will look like zero.
- Alternatively, you can start with the lowest range and dial up the range until the resistance falls into range.
Manual here. Probably, that's the right one.
answered Dec 24, 2013 at 6:27
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1\$\begingroup\$ +1 Great answer Nick. For the youngsters I wanted to add that when the meter displays
OLorOVLDit stands for "overload". It doesn't harm the meter when this happens, hence Nick's advice to start on the lowest range and dial up until you get a reading. \$\endgroup\$– Joe HassDec 24, 2013 at 12:24 -
\$\begingroup\$ @Nick, thanks for the help. I read the manual prior to asking but the table in the manual is confusing because it seems to assume some prior understanding. Now that I understand better, it makes more sense. Benefit of lower number in range is more precision, but they won't measure higher resistance. So the measurements should all be the same, but with different accuracy. However, part of my confusion was my actual results. See my new question here \$\endgroup\$– SamJan 1, 2014 at 23:13