Ammeter voltmeter reading principle, voltmeter reading method

1. See the range clearly. For example, a voltmeter commonly used in a laboratory at the junior high school level.

The measuring ranges are 0 3V and 0 15V.

2. See the graduation value clearly.

That is, how much a small grid on the dial represents. (Ammeter.)

The range 0 3a is and 0 is.

3. See the position of the watch hand (be sure to observe it from the front).

There are generally two kinds of ammeter ranges - 0, 0 3A; There are generally two types of voltmeter ranges - 0 3V, 0 15V

Because the same ammeter and voltmeter have different ranges, therefore, corresponding to different ranges, the current and voltage values represented by each cell are different, so the readings of the ammeter and voltmeter are more complicated, and the significant digits of the measured value are more prone to error. The following are the reading rules for different tables and different ranges:

1. 10 index meter reading: if the voltmeter and ammeter use 0 3V and 0 3A range, the minimum scale (accuracy) is the reading of the 10 index instrument, and the reading rules are relatively simple, only need to add an estimated reading after the accuracy.

2. 5-index meter reading: If the voltmeter uses 0 15V range, its minimum scale is the reading of the 5-index instrument, and the read value can only have one decimal place after the decimal point, and there must be one decimal place.

3. 2-index meter reading: If the ammeter uses the range, its minimum scale is the reading of the 2-index instrument, and its reading rules are similar to those of the 0-15V voltmeter, and the reading value can only have two decimal places after the decimal point, and there must be two decimal places.

The voltmeter reading method is as follows:

1) Observe whether the pointer of the voltmeter is on the zero line, if not, you can use a screwdriver to adjust the adjustment nut under the dial so that the pointer points to the zero line.

2) Estimate the size of the measured voltage, choose the appropriate range of the voltmeter, the measured voltage value is about equal to 70% of the range, the measurement effect is the best, if the size of the measured voltage can not be estimated, you can start from the maximum range.

3) After selecting the range, the voltmeter is connected in parallel at both ends of the measured voltage circuit, so that the current flows from the "+" line binding post, flows out from the "-" binding post, if the "+" mu mold of the voltmeter, the "macro slippery-" binding post is reversed, the pointer of the voltmeter will swing in the opposite direction, so that not only can not measure the size of the voltage, but also may break the pointer of the voltmeter.

4) Connect the voltmeter into the circuit correctly, do not rush to close the switch for measurement, use the moving contact of the switch to try the static contact of the switch, and observe the pointer of the voltmeter. If the voltmeter pointer does not move, it means that there is an open circuit in the circuit, and the connection of the circuit should be checked, especially whether the binding post is in good contact.

If the voltmeter pointer is deflected in the opposite direction, it means that the "+" binding post of the voltmeter is reversed and should be reconnected. If the voltmeter pointer is deflected too much and exceeds the maximum value of the selected range, it means that the selected range is small and should be replaced with a larger range. If the deflection of the voltmeter pointer is too small, not even to a small range, it means that the selected range is large and should be changed to a smaller range.

Should wait for the voltmeter pointer to stabilize before reading, reading should let the line of sight through the pointer and the dial perpendicular, now some voltmeters change to use liquid crystal display, to the reading has brought greater convenience.

The voltmeter can be directly connected to the two poles of the power supply to measure the voltage of the power supply, when the power supply is working, it provides a certain voltage value to both ends of the circuit quickly, and the voltage value provided will be reduced with the extension of the use time, so the voltmeter is often directly connected to the two poles of the power supply to measure the voltage value provided by the power supply.

The ammeter has two ranges: 0 3A; The voltmeter is also available in two ranges: 0 3V, 0 15V.

See the figure below: > the same ammeter and voltmeter have different ranges, corresponding to different ranges, and the current and voltage values represented by each grid are different.

As a result, the readings of ammeters and voltmeters are complex, and the number of significant digits of the measured values is prone to errors.

The following are the reading rules for different tables and different ranges:

Indexing meter readings.

If the voltmeter and ammeter use 0 3V and 0 3A range, the minimum scale (accuracy) is the reading of the 10 index meter respectively, and the reading rules are relatively simple, only need to add an estimated reading after the accuracy.

That is, each square of the exact cell is divided into 10 parts by visual inspection, which is not an exact value but an estimate, depending on the approximate location.

Indexing meter readings.

If the voltmeter uses the 0 15V range, its minimum scale is a 2-degree meter reading, and the read value can only have one decimal place after the decimal point, and there must be one decimal place.

Divide each cell into 5 portions and estimate which portion:

If it refers to a position somewhere in the middle between the two tick marks, it is pronounced as or, or, or, or, respectively, according to how close the hands are to the two tick marks.

Even if it refers to the positive **, it cannot be read, otherwise there will be two inaccurate numbers, that is, 2 and 5 after the decimal point, which does not meet the reading rules.

Indexing meter readings.

If the ammeter uses a range, its minimum scale is the reading of the 5-index instrument, and its reading rules are similar to those of the 0-15V voltmeter, and the read value can only have two decimal places after the decimal point, and there must be two decimal places.

Divide each exact cell into two parts, e.g. between to the exact scale, with the middle scale being close to the reading, close to the reading and close to the reading.

1. See the range clearly. For example, the voltmeter commonly used in the laboratory at the junior high school level has a range of 0 3 V and 0 15 V.

2. See how much the graduation value, that is, a small grid of the dial, represents. (The ammeter measures the clearance range 0 3a and the graduation value is, 0 is.) Eggplant Bridge.

3. See the position of the watch hand (be sure to observe it from the front).

Extended Materials. 1. The traditional pointer voltmeter comprises a sensitive galvanometer, in which there is a permanent magnet, a coil composed of wires is connected in series between the two binding posts of the galvanometer, and the coil is placed in the magnetic field of the permanent magnet and connected with the pointer of the meter through a transmission device.

2. The voltmeter has three binding posts, one negative binding post, two positive binding posts, the positive pole of the voltmeter is connected with the positive pole of the circuit, and the negative pole is connected with the negative pole of the circuit.

3. The ammeter is made according to the action of the energized conductor in the magnetic field by the force of the magnetic field.

There is a permanent magnet inside the ammeter, which generates a magnetic field between the poles, there is a coil in the magnetic field, and there is a hairspring spring at each end of the coil, and the spring is connected to a binding post of the ammeter respectively, and is connected by a rotating shaft between the spring and the coil, and there is a pointer at the front end of the rotating shaft relative to the ammeter.

Indexing instrument reading: If the ammeter and voltmeter use 0-3V, 0-3A range, the minimum scale (accuracy) is 10 indexing meter reading, the reading rules are relatively simple, only need to add an estimated reading after the accuracy to search for dates.

Indexing meter reading: If the voltmeter uses 0-15V range, then its minimum scale is 5 indexing meter reading, so the world silver can only have one decimal place after the decimal point of the reading, and there must be one decimal place, that is, the standard estimate.

Indexing meter reading: If the ammeter uses a range, then its minimum scale is 2 index meter readings, and the reading rule is that there can only be two decimal places after the decimal point of the read value, and there must be two decimal places, that is, it is also the standard estimation reading pulse.

First look at the position of the terminal post, the terminal post of the ammeter generally has 3 "-", "connected", "and" to see the number of 0 - on the dial, and "-" and "3" to see the number of 0 - 3a on the dial.

The binding post of the voltmeter generally has 3 "-", "3" and "15", which is connected to "-" and "3" to see the number of 0-3V on the dial, and "-" and "15" to see the number of 0-15V on the dial.