What is the reason why the needle of the multimeter measures the DC current in the opposite direction?
The most likely reason is that your multimeter is measuring the pen with the wrong polarity.
multimeter
Multimeters mainly include digital and pointer. Since you are using a pointer, explain it with a pointer multimeter.
1. Function of pointer multimeter
In fact, the pointer multimeter is the same as other multi-function meters, which can measure DC current, DC voltage, AC current, AC voltage, resistance and other data.
2. How to realize the measurement of direct current
The meter head of the pointer multimeter is actually a DC ammeter head. When it is necessary to measure the DC current, each gear is equivalent to connecting a resistor of different resistance in parallel with the meter head, so as to divide the current. When measuring DC voltage, a resistor of different resistance is connected in series with the meter head to reduce the voltage.
How to measure with a multimeter
Using a multimeter can be divided into several steps:
1. Observation and mechanical zero adjustment are required before use, that is, to ensure that the pointer is on the zero scale before use.
2. Select the correct gear according to the measured data. For example, when measuring DC current, the gear is selected as DCmA. Here, the DC gear must be selected, because DC is direct current and AC is alternating current. The specific gear needs to be estimated according to the actual measurement data. value.
3. The red test lead should be inserted in the "+" position, and the black test lead should be inserted in the "com" port. When measuring, the red test lead should be at the positive pole of the device under test, and the black test lead should be at the negative pole of the device under test (here is the focus of this question )
Because the characteristic of direct current is that the direction does not change with time, it has a direction, and the direction must be paid attention to when measuring. If measured as shown above, the reverse value will be displayed.
