① vernier caliper
Vernier calipers are often used to measure the length together.
Vernier calipers have 10 scale, 20 scale and 50 scale.
The accuracy of these three vernier calipers is as follows
0. 1 mm, 0.05 mm and 0.02 mm. Reading method
Is: measured value = reading of main ruler+(cursor and main ruler
The number of aligned tick marks × precision), so the cursor is used.
Do not estimate the length measured with calipers.
Because the mechanical watch adopts gear transmission, the pointer jumps every 0. 1
Jump 1 time, the pointer can't stop between two squares, so
It is impossible to estimate the reading time shorter than the minimum scale. therefore
You don't have to estimate the stopwatch reading.
③ Resistance box
Because of the special structure of the resistance box, we are conducting resistance.
During adjustment, power is supplied according to the ratio of each gear on the resistance box.
The resistance is adjusted, so the resistance of the resistance box is not connected.
Continuous adjustment, so you don't need to estimate the reading when reading.
Second, the tools that need to be evaluated.
First, the reading procedure:
1. The basic principles of reading are:
One-tenth estimation method: the lowest score is "1".
Unit, the last digit of the significant figure is the next precision.
Bit, that is, you need to estimate, if there is no estimate, it is in accuracy.
The next number is "0";
Second, the tools that need to be evaluated.
(1) scale,
② Spiral micrometer
Principle: Spiral micrometer (also called micrometer) is a vernier caliper.
A more accurate tool for measuring length. It can be used to measure length.
Accurate to 0.065438 0 mm. This is because the micrometer screw
0.5 mm forward or backward, the movable scale rotates exactly once,
A week is divided into 50 equal parts, each equal part represents 0.0 1 milli.
M, so it can be accurate to 0.0 1 mm, but it must be estimated.
One thousandth of a millimeter. Read the screw micrometer before reading.
The exposed part of the ruler is different from the general ruler.
Almost, but half a millimeter more. You can read it again.
The scale of the spiral part of the motion should be read by multiplying one bit.
Add 0.0 1mm, and two will do.
Reading formula:
Measured value = fixed scale indication+fixed scale central water
Indicates where the horizontal line is aligned with the movable ruler.
×0.0 1 mm
[Experience] 1) See if the half scale leaks and repair it.
The scale value in degrees is in millimeters;
The movable scale should be read, and three digits should be reserved after the decimal point.
Numbers.
③ Reading principle of ammeter and voltmeter: (1) each lowest score.
The degree value is in "1". The last digit of the valid figure is.
The next point of accuracy, that is, need to be estimated. If there is no estimate,
Then add "0" (2) to the next precision bit of the minimum division.
The value is 2 or 5 units, and the last significant digit is
The accuracy of the same bit (including the estimated reading), if there is no estimated reading, there is none.
"0" is required.
If the measuring range of 0~0.6A is used, its accuracy is 0.02A, that is to say, measurement.
The measurement can only be accurate to 0.02A, which is impossible.
0.0 1A, so the error appears in the hundredth ampere.
(0.0 1A), the reading can only read the percentile of ampere,
It is suggested to estimate the minimum division and half a small cell, and divide the minimum division.
Divide it into two equal parts and discard less than half, which is equal to
Or more than half of the equal parts, calculate the equal parts.
When the voltmeter is at 15V, the minimum dividing value of the dial is
0.5V/ grid, although 0.5V can be accurately read out, there is still an error.
Appears in the same number as the minimum division value, that is, volts.
Ten places. Its evaluation criterion is: divide the minimum index into points.
If it is divided into five equal parts, it is still less than half equal parts, equal to or more than.
Half division is equal division.
④ The reading method of multi-purpose ammeter can be determined according to the specific situation.
Read by combining the above three reading methods.
When the pointer position is shown by the gray triangle arrow in Figure 9, measure it.
Due to the dial, the measuring range is 10mA.
The minimum division value is not a unit. When reading 3.2 to
After that, it should not be estimated downward, so the calculation result is
3.2 ma
When the pointer position is indicated by the white triangular arrow in fig. 9, the measurement is made.
The DC voltage is 50V because the dial is the smallest.
The division value is a unit. After reading 16V, it should be the same.
Estimate the next bit, so the measurement result is16.0v.
When the pointer position is shown by the black triangle arrow in fig. 9, the measurement is made.
Is a resistor, the magnification is × 100, press the top of the dial.
According to the scale, the minimum dividing value of the dial is not a unit.
Reading, don't estimate after reading 34.
Read, so the measurement result is 34x 100Q = 3.4x 10Q.