The Usage Method of the Resistance Range of a Multimeter

The Usage Method of the Resistance Range of a Multimeter

The usage method of the resistance range of a digital multimeter is quite simple. When measuring the resistance, first adjust the range switch to an appropriate position of the resistance range according to the size of the resistance under test. Insert the red and black test leads into the VΩHz hole and the COM hole of the multimeter respectively. Then, touch the two pins of the resistance with the red and black test leads respectively. At this time, the reading displayed on the display screen is the resistance value of the resistance under test (now, many digital multimeters can also display the unit of the resistance under test, such as Ω or KΩ).

For example, when a digital multimeter measures a metal film resistor with a resistance value of 51Ω and an error of 1%, the displayed resistance value is 51.24Ω.

By the way, when the two test leads of the 200Ω range of many digital multimeters are short-circuited, a reading of a few tenths of an ohm will be displayed. This will bring about relatively large measurement errors when measuring small resistances. Therefore, when measuring small resistances below a dozen ohms, in order to improve the measurement accuracy, generally, the resistance value displayed by the multimeter when the two test leads are short-circuited should be subtracted from the actually displayed resistance value.

The above picture shows the short-circuit resistance of the 200Ω range of a normal digital multimeter. The reading shown in the picture is 0.42Ω (this reading is the contact resistance of the multimeter test leads and the internal copper sheets of the range switch, and its value is variable). Suppose a 1Ω resistance is measured, the actually displayed reading may be 1.42Ω.

For a digital multimeter with a problem in its resistance range, when the two test leads of its 200Ω range are short-circuited, the displayed resistance value is as high as 12.5Ω. For such a multimeter, when measuring small resistances below a dozen ohms, the measurement error is quite large.