The experiment that Xiao Ming did, what method did Xiao Ming need to use when doing the experiment

with a wiping cloth; Lay down horizontally; Drop dilute iodine around the coverslip and wipe off excess staining solution; And use a dropper to drop a drop of water on the slide**.

It should be washed with water; 45. Tilt down; Drop on one end and blot with absorbent paper on the other; To drip saline.

1 Do not drip with water Salt water should be dropped.

2 The coverslip should not be lowered horizontally.

3 There should be other drying procedures.

4 One should wait a little longer for the specimen to stain sufficiently.

First error:"Wipe the slides and coverslips clean with a cloth"Instead: take one slide and coverslip that has been autoclaved – to prevent contamination.

Second error:"And use a dropper to drop a drop of water on the slide**. "Instead: add a drop of normal saline.

The third error:"Gently scrape the side wall of the mouth with a clean cough"Instead: Gently scrape the inner wall of the mouth with cool boiled water.

Fourth error:"Pick up the coverslip with tweezers and lay it down horizontally"This is an obvious mistake, if you put it down horizontally, there will definitely be air bubbles, and the correct thing to do is to touch one side of the coverslip first and then slowly lower the other side.

1.Wipe dry with a rag.

2.Drop a drop of water.

3.Lay down horizontally;

4.Dilute iodine drops in 4 weeks.

I could only see that the coverslip could not be laid down horizontally, so I had to cover one side first and slowly lower it until it was fully covered.

There is also the wrong way to put the iodine solution, it should only be placed on one side, and then the opposite side is blotted with absorbent paper to make the iodine solution permeate the entire coverslip.

Drops of dilute iodine are placed around the perimeter (on one side, with absorbent paper) forceps to pick up the coverslip and lay it down horizontally (upstairs).

Clean the color after dyeing.

The fourth one doesn't know, and it is suspected that it is a dyeing error.

Hello, Xiao Ming can take the following methods to do experiments:

The first method: variable control book calendar refers to. This method we have in junior high school physics.

In class, the teacher will often mention it. If we have the influence of a certain variable on the results, we need to ensure that the other variables remain unchanged, so as to find out whether the variable has an impact on the experimental results.

The second method: the model method. When we can't directly experiment and measure the experimental subjects, we need to use the model and carry out experimental operations under the model.

The third method: the conversion method. The application of the transformation method is that in some experiments, the results of the phenomenon are not easy to display directly, and we need to convert the obtained variables into other variables for observation and measurement, which is the transformation method. For example: Cavendish State Match.

The torsion scale device is used to measure the gravitational constant.

Experiment. The fourth method: the accumulation method. As the name suggests, the accumulation method is to continuously accumulate and superimpose the results of the experiment, and then find the average.

The advantage of this is that the experimental error can be relatively reduced.

Answer: There are two kinds of dimming circuits composed of sliding rheostat and bulb, as shown in Figure A and Figure B (1) For Figure A, when the rheostat resistance is zero, the maximum current of the small bulb is: i=u rl, and the small bulb emits light normally When the resistance of the rheostat is maximum, the minimum current of the small bulb is:

i = u rl + r rheostat.

The small bulb will not go out Therefore, the brightness adjustment range of the small bulb is small (2) For Figure B, the maximum current of the small bulb is: i = u rl, and the small bulb emits light normally The voltage at both ends of the small bulb can be adjusted to zero, and the minimum current: i = 0, the light is off Therefore, the brightness adjustment range of the small bulb is large

Under the same brightness of the small bulb, the power output current of circuit B is greater than that of circuit A, and it consumes more electric energy, and when the current of the small bulb is zero and does not emit light, the output current of the power supply is not zero, and it still consumes electric energy Therefore, from the perspective of power consumption, circuit B is not economical

What is the power supply used for? What do you want to ask?

(1) This phenomenon can show that the dissolution rate is related to the size (contact area) of the substance particles The smaller the particles, the larger the contact area of the same mass, and the faster the dissolution rate.

2) This phenomenon can explain that the dissolved mass (solubility) of different substances in water is different.

3) This phenomenon can show that the temperature can increase the solubility of salt in water, but it has little effect on the solubility of salt in water.

The first shows that the dissolution rate is related to the contact area and particle size, the second shows that the solubility of different substances in water is different, and the third shows that increasing the temperature can increase the solubility of salt in water, but temperature has little effect on the solubility of salt in water.

(1) Powdered salt has a large contact area with water, so it dissolves quickly. (2) It indicates that the solubility of sucrose is greater than that of table salt. (3) It indicates that the solubility of salt does not increase with the increase of temperature.

1) The data in Table 1 or Table 2 can be seen that the rougher the contact surface, the greater the resistance of the trolley, from which it can be seen that the magnitude of the friction force on the trolley is related to the roughness of the contact surface

2) In the experiment, always let the trolley slide down from the same height of the inclined plane, the purpose of this is to make the initial velocity of the trolley when it reaches the horizontal plane equal

3) From the experimental data in Table 1 and Table 2, it can be seen that when the initial velocity of the trolley is the same, the smoother the contact surface, the smaller the resistance of the trolley, and the greater the distance of the trolley sliding

4) According to the experiment in Table 1 or Table 2, it can be seen that the smaller the resistance of the small group car, the slower the change of the trolley, and the greater the trolley sliding distance, so that if the horizontal plane is smooth, the trolley is not affected by the resistance, the trolley will remain unchanged, and the trolley will do uniform linear motion

Therefore, the answer is: (1) roughness;(Omen2) make the initial velocity of the trolley when it reaches the horizontal plane equal;

3) The less resistance the trolley is subjected to, the greater the distance the trolley can slide;(4) Straight line at uniform speed