How to read the ammeter, how to read the ammeter reading

Specify the range of the ammeter; Determine the indexing value of the ammeter; Look clearly where the watch hand rests (always from the front); Wait for the current to stabilize before reading, that is, the pointer indication of the ammeter is stable before reading.

An ammeter is made based on the action of an energized conductor in a magnetic field by the force of a 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, there is a hairspring spring at each end of the coil, the spring is connected to a binding post of the ammeter, between the spring and the coil is connected by a rotating shaft, and there is a pointer at the front end of the rotating shaft relative to the ammeter.

When there is a current passing through, the current passes through the magnetic field along the spring and the rotating shaft, and the current cuts the magnetic inductance line, so it is affected by the magnetic field force, which makes the coil deflect, and drives the rotating shaft and pointer to deflect.

Since the magnitude of the magnetic field increases with the increase of the current, the magnitude of the current can be observed by the degree of deflection of the pointer. It's called a magnetoelectric ammeter, and it's the kind we usually use in our labs. In junior high school, the ammeter used is generally 0 and 0 3 a.

Before use, it is necessary to observe: confirm that it is an ammeter; Zero tick position, measuring range; Minimum tick value. When reading, the minimum scale value should be confirmed by the measuring range, and then the result should be read from the pointer position.

The student ammeter has two ranges: a minimum scale of 0 1 A at a range of 3 amps, and a minimum scale of 0 0 02 A at a range of 0 6 amps. Rules for the use of ammeters ("two to two no").

1) The ammeter should be connected in series in the circuit. (2)" The binding post should be connected correctly. (3) The measured current should not exceed the range of the ammeter.

This section describes the dangers of measuring currents that exceed the range (pointer bending, burning out the ammeter). How do I know if the current being measured does not exceed the range? Estimate first, and then test the touch with a large number of ranges.

It is absolutely forbidden to connect the ammeter directly to the poles of the power supply without going through the electrical appliance. Guidance: The ammeter is similar to a wire, the resistance is very small, forming a short circuit, and a large current will burn out the ammeter.

Method of ammeter reading:First, the range of the ammeter is clarified; Determine the index value of the ammeter, see the position of the gauge hand (must be observed from the front), and then read after the current is stable, that is, the pointer of the ammeter indicates that it is stable before reading.

It boils down to three looks and three questions to see the range of the ammeter first, which is generally marked on the dial.

Confirm the most grid of how many amps to indicate the positive and negative binding posts of the ammeter into the circuit, observe the position of the pointer, you can read, in addition, you should choose the appropriate range of the ammeter, you can try to touch it first, if the pointer swing is not obvious, then change to a small range of the meter, if the pointer swings at a large angle, then change to a large range of the meter.

Generally, the hands are left and right in the middle of the dial, and the reading is more appropriate.

First look at the range of the ammeter, which is usually marked on the dial. After checking the most lattice to indicate how many amps, connect the positive and negative terminals of the ammeter to the circuit, and observe the position of the pointer to make a reading. In addition, it is necessary to choose an ammeter with the appropriate range.

You can try to touch it first, and if the pointer swings not obviously, change to a watch with a small range. If the hand swings at a large angle, the watch with a large range is changed. Generally, the hands are left and right in the middle of the dial, and the reading is more appropriate.

First, observe the selected range of the ammeter. Second, determine the graduation value. 3. Determine the number of current representations.

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. Look at the range: First of all, it is necessary to select different types of meters according to the range and size of the data to be measured.

2. Look at the direction of the current: Since the pointer deflection of the magnetoelectric meter is related to the direction of the surrounding magnetic field, it must be connected to the positive end of the circuit power supply from the positive pole, and the negative pole must be connected to the negative pole of the circuit power supply, and cannot be reversed.

3. Look at the use of the meter: if it is a magnetoelectric ammeter, then it should be connected in series in the circuit; If it is a magnetoelectric voltmeter, then it should be connected in parallel in the circuit, and the units of reading are different.

4. Look at the zero: Before reading, the pointer should be pointed at the "zero" point through the zeroer on the panel.

5. Look at the posture: the reading should be observed through the reflection image of the plane mirror in the dashboard, that is to say, if you want to reduce the reading error, you should let the eyes look down vertically from the top of the dashboard to see the pointer in the projection image in the plane mirror to read. The readout is accurate when the pointer appears to coincide exactly with the image inside.

6. Look at the error (uncertainty): the uncertainty or instrument error of the instrument is usually equal to the range series, and the series can be seen from the table header.

7. The reading of the magnetoelectric ammeter is based on the principle of electromagnetic damping. In order to quickly stabilize the pointer swing and facilitate the quick reading of the number, the magnetoelectric ammeter winds the coil around the closed aluminum frame, and generates an induced current in the closed aluminum frame to obtain an electromagnetic damping torque, so that the coil quickly stabilizes at the position of the indicated value.

It is generally to be estimated. It is appropriate for junior high school students to learn to read.

If the minimum scale is or, there is no need to estimate which scale the pointer is closest to and which scale is read

As shown below: <>

If the range of 0 3a is selected, each small cell of the dial is represented by , and the reading in the figure is , and the last digit "7" is estimated.

If the range of 0 is selected, each small compartment of the dial is indicated, and the reading in the figure is, there is no estimate here, and the reading is the closest to the watch hand.

The above rules are the same for junior and senior students from the middle of the middle to the university stage. However, the requirements for junior high school are not strict.