One: Fill in the blanks (65438+ 0 points for each blank, ***20 points)

1. In order to prevent fraudulent use of wireless communication facilities, high-tech means are used to shield the spread of _ _ _ _ _ _ _. The English listening tape for the senior high school entrance examination is recorded with a tape recorder, as shown in Figure (3), which is a schematic diagram of the recording head. When recording, the sound is first converted into currents with different intensities. When the current passes through the coil on the recording head, there is _ _ _ _ _ _ around the coil.

2. Spread a piece of paper on the horizontal ground and paint the surface of the ball black, so that when it falls freely from different heights, it can leave black circular spots A and B. The circular spots formed by the ball falling from a higher place are _ _ _ _ _ (choose "A" or "B"), and your judgment is based on _ _ _ _ _ _ _.

3. The picture shows the control circuit of a toy car. Xiao Ming measured and studied it, and found that the coil resistance of the motor is1Ω, and the protection resistance r is 4 Ω. When the switch S is closed, the readings of the two voltmeters are 6V and 2V respectively, so the current in the circuit is _ _ _ _ _ _ _ A and the power of the motor is _ _ _ _ _ _ _ W; If the toy car runs 1min, the heat generated by the motor coil is _ _ _ _ _ _ _ j.

4. As shown in the figure, it is a connection diagram of some lines in Xiaokejia. When the small available test pen touches the right hole of the socket, the neon tube will glow, indicating that _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _. Other electrical appliances in the room are still working normally, so the circuit at the lamp L is _ _ _ _ _ _ _ (fill in "open circuit" or "short circuit").

5. Hydropower and petroleum are two important energy sources, of which _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ is the most important energy source.

6. The basic principle of telephone is to complete the mutual conversion of sound signal and _ _ _ _ _ _ signal through microphone and receiver. Recently, the law of a western country prohibits young children from using mobile phones, because the microwave radiated by mobile phones will endanger human health to a certain extent; Microwave travels at the same speed as medium wave and long wave. The wavelength of microwave is very short, so the frequency is relatively _ _ _ _ _ _.

7. The indoor lights of a classmate's house are all working normally. When he plugged the "220V 1 1W" desk lamp into the socket, he turned off the desk lamp switch and all the lights in the room went out. The reason for this phenomenon may be a short circuit at _ _ _ _ _ _ _. (Optional "socket", "lamp plug", "lamp switch" or "lamp cap")

8. In the experiment of measuring the mechanical efficiency of pulley block, rary made a mark A on the string tangent to the moving pulley (as shown in Figure A), and then lifted the hook code with a total weight of G vertically with a pulling force of F at a uniform speed. When the hook code rose to the height of H, rary made another mark B on the string tangent to the moving pulley, and measured the distance between two points AB for 2H (as shown in Figure B) (excluding friction and rope weight). The mechanical efficiency of pulley block is _ _ _ _ _ _ _ _ _ _ _ _; If the number of hook yards is reduced, the mechanical efficiency of the pulley block will be _ _ _ _ _ _. (Select "Increase", "Reduce" or "No Change")

9. As shown in the figure, if the weight G with a gravity of 1000N is pulled up along the inclined plane at a uniform speed with a pulling force F of 500N, the mechanical efficiency of the combined machinery consisting of pulleys and inclined planes is _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

10. Heat a crystal evenly for a period of time with a stable heating device, and draw the temperature-time image as shown in the figure according to the measurement results. It can be found that if the same temperature is raised, the heat absorbed by the substance in the AB section (fill in "larger" or "smaller") is the heat absorbed in the CD section.

Second, the multiple-choice question (11-14 is a single choice; 15 and 16 are indefinite. If omitted, you will get 2 points, ***20 points).

1 1 As shown in the figure, in a family inquiry activity, Xiao Ming put a luminous bulb in the middle of the U-shaped magnet and was surprised to find that the filament was shaking. Regarding this phenomenon, the following statement is true ().

A. Is filament sloshing an electromagnetic induction phenomenon? B. silk shaking is the conversion of internal energy into mechanical energy.

C. Is the filament wobble attracted by magnets? D filament sloshing is the effect of magnetic field on current.

12. Connect the electric fan, TV set and soldering iron with the specification of "220V 100W" into the household circuit respectively, with the same power-on time. The following statement is wrong ().

A. Are the three appliances generating the same amount of heat? B. Current does the same amount of work through three appliances.

C. Do the three appliances use the same amount of electricity? Electric soldering irons generate the most heat.

13. Before the building is completed and electrified, electricians usually check whether there is any fault in the installation of home circuits. In the home circuit (part) as shown in the figure, remove the fuse and install "220V" there. 100W "incandescent lamp Ll, and then connect A and B to 220V power supply, and find that the lamp Ll emits light normally. If the switch S is closed at this time, the lamp L2 (also called "220V") will go out. 1OOW”)(？ )

A. Normal luminescence B. Luminous, but dark? C. Can't shine D. Can't judge

14, use alcohol lamp to heat the test tube, as shown in the figure, in the process of the test tube mouth cork rushed out, the following statement is correct ().

A. When steam does work on the cork, will the internal energy of steam increase?

B. the internal energy of water vapor is converted into mechanical energy of cork.

C. Is the energy conversion the same as the compression stroke of a heat engine?

D the "white gas" at the test tube mouth is formed by steam vaporization.

The nameplates of 15, A and B general lighting bulbs are marked with "Pz220- 100" and "pz1/0-25" respectively. The following statement is correct ().

A. connect two lamps in series in the same circuit. Is lamp A brighter than lamp B?

B, two lamps are connected in parallel in the same circuit, and the second lamp is brighter than the first lamp.

C No matter whether two lamps are connected in series or in parallel in the same circuit, both lamps are equally bright.

D. When both lights are on normally, the first light is brighter than the second light.

16,201165438+1In the early morning of October 3, Tiangong-1 successfully docked with Shenzhou-8 spacecraft. According to the plan, Shenzhou-9 and Shenzhou-10 spacecraft will rendezvous and dock with Tiangong-1 in turn in the next time, and the first space laboratory in China will be established. Which of the following descriptions is correct? )

Liquid hydrogen is used as fuel for launching rockets because of its large specific heat capacity.

B when tiangong-1 is launched, its kinetic energy is converted into gravitational potential energy.

C. when a rocket is launched, its mechanical energy increases.

D when tiangong-1 orbits the earth, it will slow down in the process of moving from perigee to apogee.

Third, the calculation problem (8+6+6, ***20 points)

17, the pulley block is shown in Figure A, and each pulley has the same weight. Regardless of the rope weight and friction, the weight of the object G 1 gradually increases from 200N until the rope breaks. Every time the rope is pulled at a constant speed, the object is lifted to the same height. It is known that the rising speed of the object is 0.5m/s, and Figure B records the image that the mechanical efficiency of the pulley block changes with the increase of the gravity of the object during this process. (2) What is the maximum pulling force that the rope can bear? (3) When the mechanical efficiency of the pulley block is 80%, what is the weight of the object? (4) What do you find from the image?

18, Xiaohong uses liquefied petroleum gas to boil water, and uses 60℃ hot water every day for about 100kg. After she participated in the "inquiry learning" activity, she made a simple solar water heater with the guidance of her teacher and the help of her classmates.

(1) If this water heater can heat 100kg of water from 20℃ to 60℃ every day in summer, what is the heat absorbed by the water? Known: C water =4.2× 103J/(kg? ℃)

(2) If 70% of the heat released by the burning of liquefied petroleum gas is absorbed by water, how many kilograms of liquefied petroleum gas can her family save on average every day after switching to solar water heaters? (The calorific value of liquefied petroleum gas is 8.0× 107J/kg)

(3) Please tell me the advantages of using solar water heaters. (Speak at least two points)

19, the actual power supply has a certain resistance, such as dry battery, we need to use its voltage u? And resistance r, in the actual calculation process, it can be regarded as an ideal power supply with voltage of u and resistance of 0 and resistance of r in series, as shown in figure a:

In Figure B, r 1 = 14ω, R2 = 9ω. When only r 1 is closed, the ammeter reads I1= 0.2a; When S2 is only closed, the ammeter reading is I2=0.3A Treat the power supply according to the equivalent method in Figure A, and find the voltage u and resistance r of the power supply.

Fourth, the experimental questions (6+ 10, *** 16)

At 20(6 points), Zhang Hua made two experiments with the same pulley block to measure the mechanical efficiency of the pulley block, and the data obtained were filled in the table.

According to Zhang Hua's experimental records, it can be determined that:

(1) In order to ensure the accuracy of the experiment, Zhang Hua should pull the spring dynamometer in the direction of _ _ _ _ _ _ _ _.

(2) The number of pulleys used in the experimental device is at least _ _ _ _ _ _ _, of which _ _ _ _ _ _ _ _ _ _ _ _ _.

(3) The mechanical efficiency of the pulley block measured for the first time is _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

2 1( 10), refrigerators are already widely used household appliances. Please use your physical knowledge to explore the work of refrigerator and answer the following questions.

(1) The picture shows the three-pin plug and three hole socket of the refrigerator. The wire marked with the letter E on the plug should be connected to _ _ _ _ _ _ _ of the refrigerator; When the refrigerator works normally, the voltage between the two pins marked with letters L and N on the plug is _ _ _ _ _ _ _ _ V.

(2) Xiao Ming saw the nameplate of his refrigerator, in which "power consumption:1.2kw h/24h" means that the refrigerator consumes1.2kw h in normal use for one day, but if it works normally according to the nameplate for one day, it consumes _ _ _ _ kw h. 。

(3) This calculation result is quite different from the relevant parameters provided on the nameplate of refrigerator. After actual measurement, Xiao Ming, who loves brains, found that the power consumption of the refrigerator is indeed as shown on the nameplate. After consulting the information, he found that this was caused by the intermittent working characteristics of the refrigerator. Then the cumulative working time of the refrigerator compressor every day is _ _ _ _ _ h.

(4) When the refrigerator door is opened in summer, "white gas" often appears near the refrigerator door, and the state change process of "white gas" is _ _ _ _ _ _ _; There will be a thick layer of frost on the wall of the freezer, and the state change process of frost formation is _ _ _ _ _ _.

(5) Although the refrigerator can transfer the energy inside the refrigerator from low temperature to high temperature, this process consumes electricity. This shows that the transfer and transformation of energy is _ _ _ _ _ _.

(6) Modern refrigerators use new refrigerants such as R 134a and cyclopropane, which will not destroy _ _ _ _ _ _ in the upper atmosphere of the earth, so as to prevent excessive _ _ _ _ _ _ _ _ _ in the sunlight from reaching the ground and avoid further deterioration of the earth's ecological environment.

(7) Please tell me the specific measures to save electricity when using the refrigerator: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.

Five: Ask questions (8 points for each question, ***24 points)

22. The picture shows the circuit of the small red connection in the experiment of "measuring the electric power of small light bulb". The rated voltage of the small bulb is 3.8V, and the power supply voltage is 6V.

(1) Please connect the circuit in Figure A with a stroke line instead of a wire.

(2) Adjust the sliding rheostat to make the bulb glow normally. The ammeter indicates as shown in Figure B. At this time, the circuit current is ______A, and the rated power of the small bulb is _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.

(3) Xiaohong connects the circuit according to the same circuit diagram. When the last wire is connected, the light bulb immediately emits bright and dazzling light and goes out soon. After checking, it is found that the connection is correct. Please help Xiaohong find out the improper operation in the experiment:

①______________________________________; ②______________________________________。

(4) Without changing the circuit connected above, the experiments that can be completed are: _ _ _ _ _ _ (write any one).

(5) If the voltmeter's range of 0 ~ 15V is damaged, and the range of 0 ~ 3V can only be used normally, it is required to measure the rated power of the small bulb with the original equipment. Please draw the circuit diagram of your design in the dotted box above. (2 points)

23. Measure the resistance of unknown resistance Rx with power supply, sliding rheostat, constant resistance R0 (known resistance) and two ammeters A 1 and A2. The students designed the following three circuits: A, B and C.

(1) After discussion, it is considered that the best scheme for measuring the resistance of the unknown resistor Rx is the circuit shown in Figure _ _ _ _ _;

(2) Xiaoyu carried out the experiment according to the best scheme. In an experiment, the pointer of ammeter A 1 is I 1, and the pointer of A2 is I2, so the measured resistance Rx = _ _ _ _ _ _ _ _ _ _ _ _ _ _(2 points).

(3) In a certain measurement, Xiaoyu found that no matter how to move the slider P of the sliding rheostat, the readings of the two ammeters A 1 and A2 are always equal, that is, I 1=I2, thus judging that the fault at Rx is _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _;

(4) The function of the sliding rheostat in this experiment is _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.

(5) If he just "touched" it during the experiment, he found that the ammeter pointer was quickly adjusted to the maximum scale. The reasons may be:

①________________________________________; ②_________________________________________

After learning the calorific value of fuel, Xiao Wang designed an experiment to explore the calorific value of alcohol and paper.

(1) The experimental device is shown in Figures A and B. Do you think the installation order of the four devices in the figure is _ _ _ _ (bottom-up/top-down)? (2 points)

(2) In order to ensure the reliability of the experimental conclusion and facilitate comparison, Xiao Wang should store the quality of alcohol, paper and water in two beakers respectively, and both beakers should be kept in _ _ _ _ _ _ _ _. (2 points).

(3) The experimental data are recorded in the following table:

fuel

Water temperature before heating℃

Water temperature when the fuel burns out℃

The calorific value of fuel j? kg- 1

alcohol

15

35

2.4× 106

a scrap of paper

15

25

?

According to the data in the table, the calorific value of waste paper is calculated as _ _ _ _ _ _ _ _ j/kg. (2 points).

(4) Compared with the actual situation, the experimental fuel calorific value is _ _ _ _ _ (choose "large" or "small"). What do you think are the main reasons for this situation: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.