Where is the real question of the senior high school entrance examination?

Fill in the blanks

In the circuits shown in 1 and figure 1, the resistance of the resistor R 1 is 10? . Turn on the switch S, the indication of ammeter A 1 is 2A, and the indication of ammeter A2 is 0.8A, so the resistance of resistor R2 is _ _? .

2. When exploring the relationship between the voltage across the resistor and the current flowing through the resistor, Xiaodong chose two constant-value resistors, R 1 and R2, to do experiments respectively. He drew the image shown in Figure 2 according to the experimental data. Please compare the size of the resistor R 1 and R2 according to the picture, r 1 _ _ R2. (optional "greater than", "equal to" or "less than")

3. The resistance of a conductor is 20 ohms. If the current passing through the conductor is 0.3 A, the amount of charge passing through the conductor section within 10 second is _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.

4. In the circuit shown in Figure 3, the power supply voltage remains unchanged. Close the key S. When the slider P of the sliding rheostat moves to the left, the reading of ammeter A will be _ _ _ _, and the difference between the readings of voltmeter V and voltmeter V 1 will be _ _ _ _ _ _. (Select "Greater", "Smaller" or "No Change" for all)

5. In the circuit shown in Figure 4, the power supply voltage is constant, R2 =10Ω. When S 1 is closed and s2 is open, the ammeter indicates 0.2A, and when both switches are closed, the ammeter indicates 0.5A, so the resistance R1= _ _ Ω.

6. As shown in Figure 5, when the conductor is connected between circuits A and B, the conductor and the bulb are connected in _ _ _ _ _. If different conductors are connected between A and B respectively and the switch is closed, the resistance of different conductors can be judged by observing and comparing _ _ _ _. If the resistance of the two conductors is not much different, you can use a _ _ _ meter instead of a light bulb for further judgment.

7. As shown in Figure 6, the power supply voltage remains unchanged, and the maximum resistance value of the sliding rheostat R0 = 20Ω. When only the switch S 1 is closed and the slider P is placed at the leftmost end A, the current representation number is 0.2A; when the switch S 1 and S2 are closed, the slider P is placed at the rightmost end B, the current representation number is 0.6A, the constant resistance R1= _ _ _ Ω, and the power supply voltage U = _ _ _ V. ..

8. Using the circuit shown in Figure 7, when studying the relationship between the current passing through the conductor and the resistance, the voltage across the conductor should remain unchanged. In the experiment, the resistance value of Rx is constantly changed, and the volt number is kept constant by adjusting the sliding rheostat, and the relationship image between I and R is obtained, as shown in Figure 8. The conclusion that can be drawn from the image is _ _ _ _ _ _ _ _ _ _; In this experiment, the voltmeter is always kept at _ _ _ _ volts.

9. Connect a pencil lead at each end of a 3V power supply, and the current through pencil lead is measured to be 0. 15A, so the resistance of pencil lead is _ _ _ _ Ω; If the voltage on this pencil lead is increased to 6V, the current through it is _ _ _ _ A. ..

10, when Xiao Juan explored the relationship between the current on the resistor and the voltage at both ends, he drew the recorded experimental data into an I-U diagram as shown in Figure 9. According to the figure, the resistance of A is _ _ Ω, and the total resistance of A and B after two resistors are connected in series is _ _Ω; These two resistors are connected in series and connected to a power supply with a voltage of 9V, and the current in the circuit is _ _ _ _ A；; Two resistors are connected in parallel and then connected to a 9V power supply. The current in the main circuit is _ _ _ _ _ A. ..

1 1, the circuit shown in figure 10, close the switch, and move the slider p of the sliding rheostat to terminal B. The ammeter reading is _ _ _ _ _ _, and the voltmeter reading is _ _ _ _. (Select Smaller, Same or Larger)

As shown in figure 12 and figure 1 1, there are two resistors with resistance values of 5 Ω and10 Ω in the dotted box. Xiao Ming wanted to know the connection mode, so he used a 3V power supply, an ammeter and a switch to test. After closing the switch, the ammeter reads 0.2A, so the connection mode of the two resistors is _ _ _ _. If you want to increase the reading of the ammeter, the measures you can take are _ _ _ _ _.

13, and the relationship between the current in two circuit elements A and B and the voltage at both ends is as shown in figure 12, then Ra = _ _ _ _ ω. If they are connected in series and connected to the power supply, the current in the circuit is 0.3A and the power supply voltage is _ _ _ _ V. ..

Second, multiple choice questions

3、2009? Henan LED lamp is a new type of high-efficiency and energy-saving light source, and its core component is LED. Diodes are made of which of the following materials?

A. Ceramic materials B. Metal materials

C. Semiconductor materials D. Superconducting materials

4、2009? When the temperature in Yichang drops to a certain extent, the resistance of some substances will become zero, which is called superconductor. The following objects can be made of superconductors.

A. household fuse B. filament of incandescent bulb C. heating wire of electric furnace D. transmission conductor

5、2009? Yichang is connected in series with two resistors R 1 and R2 with different resistance values, and the total resistance is

A. between two resistors b, it is smaller than any one resistor.

C is greater than any resistance. D can be equal to one of the resistances.

7、2009? There are two resistors in Yulin City, with resistance values of 30 and10Ω respectively. If connected in series, the total resistance is a.40Ω B.30Ω C.20Ω D.7.5Ω. ..

8、2009? As shown in figure 16, Fuzhou is a schematic diagram of the pressure sensor designed by Tong Tong, in which the upper end of the spring is fixed with the slider P of the sliding rheostat, there is a telescopic line between AB, and R 1 is a constant resistance. When the switch S is closed and the pressure F increases, the change of ammeter and voltage indicator is B.

A. the current means bigger, and the voltage means smaller.

B. Current means smaller, and voltage means larger.

C. The ammeter and voltage indicator are relatively large.

D. the ammeter and voltage indicator have become smaller.

9、2009? Qiqihar city is shown in figure 17 circuit, the power supply voltage is constant, the switch s is closed, and the slider p of the sliding rheostat moves to the right (assuming the filament resistance is constant). The following statement is correct.

A. the voltmeter and current indicator become smaller.

The ratio between the voltmeter and the current indicator becomes larger.

C. the voltage indicator becomes larger and the light becomes dim.

D. the current indicator becomes larger and the light becomes brighter.

3. Inquiry and experiment questions

1、2009? In order to explore the problem of series resistance, Xiao Fang designed an experimental circuit as shown in figure 18, in which R 1 is a resistance box, R2 is a constant resistance, R represents the total resistance (equivalent resistance) of R 1 and R2 in series, an ammeter measures the current I in the series circuit, and a voltmeter measures the voltage U between point A and point B. The data recorded by Xiao Fang through experiments are as follows. According to the experimental data in the table, please summarize the relationship between the total resistance r and the resistance R 1: _ _ _.

R 1/？ 5 10 15 25 35 45

u/V 12 12 12 12 12 12

I/A 0.6 0.48 0.4 0.3 0.24 0.2

R/？ 20 25 30 40 50 60

2、2009? Beijing Xiaolong wants to measure the resistance of resistor Rx with a voltmeter and a known resistor R0. Xiaolong chose the equipment that meets the experimental requirements and connected some experimental circuits, as shown in figure 19. The requirements of the experimental circuit designed by Xiaolong are as follows: only when the switch S and S 1 are closed, the voltmeter measures the voltage u1across the resistor R0; When only switches S and S2 are closed, the voltmeter measures the voltage U2 across the power supply.

(1) Please add only one wire according to Xiaolong's design requirements to complete the connection of the experimental circuit shown in Figure 19;

(2) Please use U 1, U2, R0 to represent Rx, where Rx = _ _ _.

3、2009? Tianjin (6 points) in the experiment of "measuring the resistance of unknown resistor R";

(1) Please connect the device in Figure 20 to an experimental circuit and use a stroke line instead of a wire.

(2) During the second measurement, please use the voltmeter and current indicator shown in Figure 2 1 to fill in the corresponding blanks in Table 2.

Table 2

Multiply by 1 23

Voltage /V 1. 1 2.3

Current //A 0.22 0.46

(3) Processing the experimental data recorded in Table 2, it is concluded that the resistance value of the resistor R to be measured is _ _ ω.

4、2009? In the experiment of measuring the constant resistance Rx with a resistance of about 5 Ω in Henan, Xiao Ming and Xiao Liang used the equipment shown in Figure 22.

(1) The physical circuit connection is completed by using the travel line instead of the wire. When the slider of the sliding rheostat is required to slide to the right, the resistance connected to the circuit becomes smaller.

(2) After Xiao Ming connected the last wire, he saw that the readings of voltmeter and ammeter were very large immediately. His two mistakes in the experimental operation are _ _ _ _ _ _ and _ _ _ _ _.

(3) After correcting the error, Xiao Ming changed the voltage and current at both ends of Rx. The measured secondary resistance is r 1 = 5. 1ω, R2 = 5.3ω. During the third measurement, the ammeter reading is 0.5A, and the voltmeter reading is shown in Figure 23, so R3 = _ _ _ ω, and the experimental value should be Rx = _ _ _ ω.

(4) In an experiment, the voltmeter failed to be used. Liang Xiao used the original ammeter and sliding rheostat, added a constant resistor R0 and a single-pole double-throw switch, and designed the circuit as shown in Figure 24. When measuring, close S 1, turn S2 to L, and the ammeter indicates I1; When S2 is set to 2, the ammeter indicates I2, and Liang Xiao indicates the measured resistance Rx= I 1/ I2? R0. After careful analysis of the circuit, Xiao Ming found that Xiao Liang's design was unreasonable, because _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.

5、2009? Xiaoming, Hebei wants to measure the resistance of a small light bulb with a rated voltage of 2.5V and a normal working current of less than 0.3A.

(1) Figure 25 is the physical circuit that Xiao Ming has not finished. Please draw lines instead of wires to complete the physical diagram. (It is required that the sliding rheostat connected to the circuit has the largest resistance)

(2) After connecting the circuit, Xiao Ming conducted an experiment, and the recorded data are shown in the following table. Please carefully analyze the experimental data and answer the following questions:

① There are obvious erroneous data in the table. Please point out the wrong data and analyze the reasons. ____________________________________________ 。

(2) The resistance of a small light bulb when it emits light normally is _ _ _ Ω.

(3) After completing the above experiment, Xiao Ming wants to measure the resistance of a resistance wire Rx (about10Ω) with the original circuit. He replaced the light bulb with a resistance wire, closed the switch and found that the voltmeter was damaged. Without changing the connection mode of other circuit components, he removed it. Xiao Ming also finished the experiment. Please briefly describe the experimental steps and write the final expression for calculating Rx. (It is known that the maximum resistance of sliding rheostat is R0)

Experimental steps: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Expression: rx = _ _ _ _ _ _

6、2009? The following Nanchang is an experimental report written by Xiao Ming after he finished the experiment. Please help him finish it.

Experimental name volt-ampere resistance measurement

Experimental principle r = u/I

Please draw the required equipment in the dotted box with the designated circuit device symbols (warm reminder: it is not necessary to draw the circuit diagram).

Experimental steps (omitted)

Please design the data record form of this experiment for experimental data.

Voltage u/v 2.0 2.5 2.8 7.5

Current I/I/A 0.26 0.30 0.32

Experimental development

This experimental device can also be used to measure the power of a small light bulb. Xiao Ming chose a small light bulb with a rated voltage of 2.5V for the experiment. The picture on the right shows some experimental data. Please fill in the blanks in the form completely and explain the basis for filling in _ _ _ _ _ _ _ _ _ _ _.

7、2009? Guangzhou (5 points) Measure the resistance value of resistor R with the instrument shown in Figure 20.

(1) Connect the circuit of Figure 20 to the correct measuring circuit.

(2) The sliding rheostat protection circuit in the circuit. Therefore, before the switch is closed, its slider should be moved to the _ _ _ end (fill in "left" or "right"); In the process of experiment, sliding rheostat has another function of _ _ _ _ _.

(3) If the readings of ammeter and voltmeter in the circuit are as shown in Figure 2 1, the readings of ammeter and voltmeter are _ _ _ _ _ _.

V. Comprehensive application problems

1、2009? Lanzhou City (6 points) has the circuit shown in Figure 28, and the power supply voltage remains unchanged. In figure A, the switch S is closed, the voltage is 4V, and the current is 0.4A; in figure B, the switch S is closed, and the voltage is 6V. Q:

(1)R 1 and the resistance of R2;

(2) The current representation in Figure B. ..

2、2009? Students from a class of a science and technology group in Changsha designed a simple electronic tension meter. Fig. 29 is its schematic diagram. The object A placed on the horizontal ground is connected to the pull ring through a hard spring. The upper end of the spring is fixed with the metal slider P (the resistance of the spring is ignored, and the contact between P and R2 is good, and the friction is ignored). It is known that the mass of object A is 100kg and the fixed resistance is R 1 = 6? R2 is a uniform resistance wire with a length of 6cm (the resistance value is proportional to its length), and its maximum resistance value is 24? , the power supply voltage is 6V, and the ammeter range is 0 ~ 06A. When the tab is not pulled, the metal slider P is just at the A end. It is known that the relationship between spring elongation length △l and vertical upward pulling force F is shown in Figure 30. Q:

(1) Change the dial of ammeter to the dial of tensiometer. Where should the zero scale of the dial of tensiometer be marked?

(2) Close the switch. When the current is 0.6A, what is the resistance in the R2 path?

(3) Under the condition of ensuring the safety of the circuit, what is the pressure range of block A to the ground? (take g= 10N/kg)