Ask 20 10 Jiangxi teacher recruitment exam junior high school physics questions and answers.

Physical part ***60 points

1. Multiple-choice questions (6 small questions in this question, 2 points for each small question, *** 12 points)

1. The following statements about electricity and magnetism are incorrect.

A. Shen Kuo, a scientist in China, first discovered that the geographical pole does not coincide with the geomagnetic pole.

B magnetic poles of the same name repel each other and magnetic poles of different names attract each other.

C. the generator can convert mechanical energy into electrical energy.

The magnetic field strength of D electromagnet has nothing to do with the current passing through the electromagnet coil.

2. Among the four phenomena shown in Figure 1, the one that belongs to decompression is

3. We have experienced the following sound phenomena, which can explain the causes of the sound.

A. The alarm clock in the bell jar is ringing. After the air in the bell jar was pumped out, the bell became obviously smaller.

B touching a tuning fork that is making sound to a calm water surface will arouse water waves on the water surface.

C standing on the river bank and talking loudly will scare away the fish swimming by the river.

D. Knock on one end of a long steel pipe, and two knocks can be heard at the other end.

Playing barefoot by the river under the scorching sun, you will find that the sand burns your feet, but the river is cold. This is mainly because

A. the specific heat capacity of sand is very high. The density of sand is high.

C. water has a large specific heat capacity and a low density.

5. When Xiao Fang was exploring "What is the size of buoyancy (Archimedes principle)", he did the experiment as shown in Figure 2. In the four-step experiment, the relationships among the indexes F 1, F2, F3 and F4 of the spring scale are as follows.

A.F2-F3 = F4-f 1 B . f 1 = F4 F2 = F3

C.f 1 = F2 = F3 = F4 D. None of the above conclusions are correct.

6. In order to save electricity, many lighting lamps in building corridors are equipped with acousto-optic switches. After a period of use, people found that the light bulb was easy to be damaged, so someone connected two 40W light bulbs in series instead of the original 1 40W light bulb and connected them in the original place, thus achieving the purpose of prolonging the service life of the light bulbs. If the influence of temperature is not considered, the total power consumed by the two lamps will be improved.

A. equal to 80w b. equal to 40w c. equal to 20w d. equal to 10W.

Second, fill in the blanks by drawing lots (this question is 6 small questions, the seventh and ninth small questions are 4 points, 12 small questions are 3 points, other spaces are 1 points, *** 17 points).

7. When Xiao Ming's family read the meter in April, the reading of the electric energy meter in May is as shown in Figure 3. What is the electricity consumption of his household appliances this month? H. if 1kW? H the electricity bill is 0.58 yuan, so the electricity bill payable by Xiao Ming's family this month is _ _ _ _ _. Xiao Ming wants to measure the power of the TV set at home with an electric energy meter, so he connects the TV set to the home circuit and turns off other electrical appliances. It is measured that the dial of the electric energy meter rotates 50 times in 10min. The power of this TV set is _ _ _ _ _.

8. The drifting on the Yuanyang River in Jingshan, which has the reputation of "the first drifting in Central China", is a favorite project for tourists. When a drifter sits down the river on a rubber raft, he takes the rubber raft as a reference _ _ _ _ _ _ _. People often get wet when drifting, and it will be a little cold when the wind blows ashore. This is because the water has evaporated _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.

9. The value of the sunken ship Nanhai No.1, which is 200 meters below the sea surface, is comparable to that of the Qin Terracotta Warriors and Horses. Salvage personnel are adopting the method of sinking a large iron box (caisson) into the seabed, putting the sunken ship into it as a whole, and then lifting it out of the sea with the buoyancy of several inflatable airbags with the volume of 10m3. The pressure of seawater on the sunken ship is _ _ _ _ _ _ _ Pa, and the buoyancy of each airbag in seawater is _ _ _ _ _ n (ρ seawater =1.03x103kg/m3, g is 10N/kg).

10. In order to prevent personal injury caused by electric shock, in newly-built buildings, most main switches connecting users are equipped with _ _ _ _ _ _ protectors; In order to avoid the occurrence of lightning disasters, the top of high-rise buildings must be installed with _ _ _ _ _ _ _ _ _ _ _ _ _ _, and connected with the earth through thick metal wires. Never hide under a big tree during a thunderstorm.

1 1. The "Chang 'e to the Moon" project, which marks another significant progress in China's space field, will be implemented in the second half of this year. The surface of the moon is almost vacuum. When two astronauts land on the moon, they must use radio communication equipment to talk to each other. This shows that _ _ _ _ _ _ _ can propagate in a vacuum, but vacuum cannot _ _ _ _ _ _ _.

12. Complete the following figure.

(1) According to the propagation direction of incident light and refracted light, draw a suitable type of lens in the dotted box in Figure 4.

(2) Draw the gravity diagram on the torch of the 2008 Beijing Olympic Games as shown in Figure 5.

(3) The relay is a device that indirectly controls the high-voltage and high-current circuits by making and breaking the low-voltage and weak-current circuits. Please draw the battery symbol at the position where the low-voltage power supply is connected in the schematic diagram of the electromagnetic relay shown in Figure 6.

Third, experiment and inquiry (there are 4 small questions in this question, 13 and 14 each with 3 points, 15 7 points, 16 8 points, ***2 1 point).

13. When using the thermometer, first observe its _ _ _ _ _ _ and see the dividing value clearly. When an experimental group practiced measuring liquid temperature with a thermometer, the four students did as shown in Figure 7, in which the correct one was (fill in the label); When the doctor took Xiaohong's temperature, the thermometer read as shown in Figure 8. At this time, Xiaohong's temperature is _ _ _ _ _ _ _℃

Properties of object distance image and its application

The size is upside down

U & gt2f Inverted Real Image F

F<u & lt2f Projector for Enlarging Real Image v > 2f

U< magnifies the upright virtual image-

14. The following table is a table designed by Xiaojun when exploring the imaging law of convex lens. Please review your exploration process and fill in the form completely.

15. Xiao Qiang used a power supply with a voltage of 6V, a small bulb with a rated voltage of 2.5V, and a sliding rheostat, an ammeter, a switch and wires that met the experimental requirements. Figure 9 shows the unfinished physical circuit of Xiao Qiang.

(1) Please use a stroke line instead of a wire to help Xiao Qiang connect the physical circuit completely;

(2) Xiao Qiang turned on the circuit closing switch and moved the rheostat slider P, and found that the small light bulb was always closed, but the voltmeter had instructions and the ammeter had no instructions, so the cause of the failure may be (write one casually);

(3) After troubleshooting, Xiao Qiang closes the switch and moves the slider P to a certain position. The voltmeter indicates 2.2V to measure the rated power of the small bulb, and the slider P should slide to the end (select "left" or "right");

(4) Xiao Qiang records the readings of several groups of voltmeter and ammeter by moving the slider P, and draws the U-I diagram as shown in figure 10. According to the information provided by the U-I diagram, it can be calculated that the rated power of the small bulb is ___ W, and the resistance of the small bulb is _ _ _ _ _ Ω when the voltage across the small bulb is1.5v..

16. Xiaohua tied a nut at one end of a long line to make a simple pendulum as shown in figure 1 1 Observing the swinging process, Xiaohua found that the time spent swinging the nut seemed to be the same. So he has two conjectures about the time t required for the nut to swing back and forth once: (a)t may be related to the mass m of the nut; (b)t may be related to the length l of the line.

(1) In order to verify the conjecture, in addition to wires and nuts with known mass m, Xiaohua also needs equipment: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.

(2) Under different conditions, Xiaohua measured the time t taken for the nut to swing back and forth once, and obtained some data in the following table.

Mass of serial number nut m/length of g line l/cm time of swinging back and forth t/s

1 30 120 2.2

2 40 120 2.2

3 50 120 2.2

4 50 90 1.9

5 50 60 1.5

(1) In order to study the relationship between t and quality m, the data with serial number _ _ _ _ _ _ _ can be analyzed;

② Through the analysis of the data in the table, a preliminary conclusion can be drawn: T has nothing to do with _ _ _ _ _ _ _ _.

(3) It is found in the experiment that it is difficult to measure the time taken for the nut to swing back and forth. Please help Xiaohua design a better measurement method: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Four, practice and application (this question 10, to write the main calculation formula, the necessary text and the unit of physical quantity)

17.On April 18, 2007, the new high-speed train "Harmony" EMU began to gallop on major railway trunk lines, thus opening the curtain of the sixth national railway speed increase. As shown in Figure 12, CRH2 EMU consists of five cars, with a total power of 6000kW, a maximum traction power of 4800kW and a maximum running speed of 200 km/h. ..

(1) What is the distance that a train set travels on a straight track for 3min at maximum speed and maximum traction power? What is the resistance of the train set in this process?

(2) In order to ensure the normal operation of the train set, the power consumption of the electric water heater for drinking water for passengers in each carriage should not exceed 2800W W ... How much heat can the electric water heater in the car generate at most in 5 minutes? How much 20℃ water can this heat raise to 70℃? 【 The specific heat capacity of water is 4.2× 103J/(kg? ℃)]

(3) Observe the shape of the front carefully, and please talk about the benefits of this design.

Reference answers and scoring instructions for physics test questions

First, multiple-choice questions (2 points for each small question, *** 12 points)

1.D 2。 B 3。 B 4。 C 5。 A six. C

Second, fill in the blanks by drawing lots (6 small questions in this question, 2 points for the third small question in the seventh question, 2 points for each small question in the ninth question, 12 small questions 1 point for each picture, 1 point for other empty questions, * *1point).

7. 100; 58; 100 8. Still; 9.2.06× 106; 1.03x10510. Electric shock (or electric leakage); lightning conductor

1 1. electromagnetic wave; Voice 12. As shown in the figure (as long as the lens with thin center and thick edge is drawn in Figure 9).

Third, experiment and inquiry (there are 4 small questions in this question, 13 and 14 each with 3 points, 15 7 points, 16 8 points, ***2 1 point).

13. Range (or measuring range); ④; 37.8 (per space 1 point, ***3 points)

14. Reduce; Fall head; Magnifier (per grid 1 minute, ***3 points)

15.( 1) See the following figure (voltmeter range 1, connected to the right end of small bulb or rheostat 1 left end, ***2).

(2) the small bulb is broken (or the filament of the small bulb is broken, the lamp holder is in poor contact, and the lamp holder terminal is in poor contact) (2 points)

(3) Right (1)

(4)0.5; 10 (1 point per space, ***2 points)

16.( 1) stopwatch (or timer, clock, stopwatch); Ruler (or ruler) (1 point per grid, ***2 points)

(2)① 1, 2 (or 1, 3 or 2, 3 or 1, 2, 3) (2 points, 1 label does not score)

② The mass (or mass, m) of the nut; Line length (or length, L) (1 dot per space, ***2 dots)

(3) Measure the time required for the nut to swing back several times in a row, and then divide this time by the number of times of swinging back (2 points).

Four, practice and application (this question 10, to write the main calculation formula, the necessary text and the unit of physical quantity)

17.( 1) Distance traveled by train sets within 3 minutes.

..............................., two points.

or

Work completed within 3 minutes of towing.

.................... 1 point

Maximum traction of train sets

.......................... 1 min.

Or you can know the maximum traction of the train set.

........................., two points.

Because the car group moves in a straight line at a uniform speed, the resistance is equal to its traction ... 1 min.

(2) If all the electric energy consumed by the electric water heater is converted into heat for 5 minutes, the maximum heat that the electric water heater can generate in a compartment for 5 minutes.

.......................... 1 min.

Quality of heatable water

.............................., two points.

(3) This question is an open question. As long as students are reasonable, they can be given points. (2 points)

Reference answers are:

① The streamlined front can reduce the air resistance when driving at high speed.

(2) The high air velocity in the upper part of the locomotive and the low air velocity in the lower part can reduce the pressure (pressure) on the track when the locomotive runs at high speed, thus reducing the resistance and noise.

Note: If there is no formula in the calculation process, you can't score. If there is no writing unit for the calculation process or result, deduct 1, and deduct 2 points at most for this question.