Facing the 2022 High School Entrance Exam Physics Model
Shandong Binzhou Paper
(This paper has 24 questions in total, and the whole paper has four major questions, with a full score of 100 points)
Paper Ⅰ (multiple choice questions, 48 points in total)
1. Single choice Question (15 questions in this question, 48 points in total)
1. Among the following estimated data, the one closest to reality is ( ).
A. The temperature of bath water is about 60°C; B. The normal walking speed of a person is more than 5m/s;
C. The height of middle school students' desks is about 80cm; D. The mass of the physics textbook is about 2kg
[Answer] C.
【Analysis】A. The temperature of bath water is about the same as that of the human body, about 40°C, so A is not realistic.
B. The normal walking speed of a person is around
, so B is not realistic.
C． The height of middle school students is about 160cm, and the height of the desk is about half of the height of middle school students, about 80cm, so C is realistic.
D. The mass of an apple is about 150g, and the mass of a physics textbook is about the same, about 150g=0.15kg, so D is not realistic. So the answer is C.
2. Regarding the sound phenomenon, the correct one of the following statements is ().
A. Ultrasonic waves can propagate in vacuum;
B. Sound can be heard as long as the object vibrates;
C. The harder you hit the drum, the higher the pitch of the sound;
D. The beautiful symphony sometimes becomes noise
[Answer] D.
[Analysis] Ultrasound is a type of sound wave, and its propagation also requires a medium, so A is wrong.
Sound is produced by the vibration of an object, but the vibration of the object does not necessarily mean that we can hear the sound, because when the sound reaches our ears, we also need a medium to propagate the sound. For example, if an object vibrates in a vacuum cavity, we cannot hear its sound, so B is wrong.
Beating the drum hard will increase the vibration amplitude of the drum surface and the sound (loudness) of the drum, but its pitch will not be affected by the strength of the drum, so C is wrong.
In a broad sense, any sound that affects people's normal activities, makes people feel irritated, and affects people's health is called noise; when a beautiful symphony affects people's activities, it becomes noise; therefore, D is correct.
3. Among the various light phenomena in the column below, the incorrect explanation is ( ).
A. The formation of solar and lunar eclipses is due to the fact that light propagates along straight lines in the same uniform medium;
B. We can see non-luminous objects because the light reflected by the objects enters the human eye;
C. The chopsticks inserted diagonally into the water appear to be bent due to the refraction of light;
D. The circular light spot that appears under the dense shade of trees during the day is the virtual image formed by the sun passing through the small hole
[Answer] D.
[Analysis] Solar and lunar eclipses are formed because the moon or the earth blocks light. This is the reason why light propagates in straight lines in the same uniform medium, so statement A is correct;
Any object we see It is all caused by the light from the object entering our eyes, so it is correct that we can see non-luminous objects because the light reflected by the object enters the human eye;
Chopsticks inserted obliquely into the water appear to be bent because What is formed by the refraction of light is also correct;
The circular spot that appears under the dense shade of trees during the day is formed by the sun passing through the small hole. It is the phenomenon of light actually hitting the ground. It is not a virtual image, but a real image , so this The statement is wrong. The correct answer is D.
4. Thermal phenomena can be seen everywhere in our lives. Which of the following statements about thermal phenomena is incorrect ( ).
A. When boiling water, the " white gas " coming out of the spout is the water vapor generated by the vaporization of water;
B. In summer, popsicles taken out of the freezer emit "white gas", which is a phenomenon of liquefaction;
C. Washed clothes should be dried in a sunny and ventilated place, because the speed of liquid evaporation is related to the temperature and air flow speed;
D. The mothballs placed in the wardrobe gradually became smaller and finally disappeared. This is a sublimation phenomenon
[Answer] A.
[Analysis] When boiling water, the "white gas" coming out of the spout is caused by the vaporization of water to generate water vapor, and then the water vapor turns into small water droplets when it is cooled. It is not vaporization, but liquefaction. This is a common phenomenon, so this kind of The statement is wrong;
The popsicles taken out of the freezer in summer emit "white gas", which is the water vapor turning into small water droplets when it is cold. This is a liquefaction phenomenon. This statement is correct;
Washed clothes should be dried in the sun and ventilated This is because the speed of liquid evaporation is related to the temperature and air flow speed. This statement is correct;
The mothballs placed in the wardrobe gradually became smaller and finally disappeared. This is the process of directly changing from solid to gaseous state, which is a phenomenon of sublimation. This statement is correct. The answer to this question is A.
5. Regarding the internal energy of an object, which of the following statements is correct ( ).
A. As the temperature of the same object decreases, its internal energy must decrease;
B. Between any two objects, heat transfer ;
C will occur. An object with a temperature of 0℃ has no internal energy;
D. Objects of the same mass and temperature must have the same internal energy
[Answer] A.
[Analysis] The internal energy of an object is related to its temperature. If the temperature of an object decreases, its internal energy will definitely decrease. This statement is correct.
Heat transfer occurs between substances with temperature differences, so statement B is wrong.
Any object has internal energy. The temperature of the object only affects its internal energy, so C is wrong.
In addition to the internal energy of an object being related to its mass and temperature, the internal energy is also related to the properties and state of the substance, so statement D is wrong. Therefore the correct answer is A.
6. The correct understanding of the concept of density is ( ).
A. The density of a certain substance is proportional to its mass; B. Density refers to the mass of substance per unit volume;
C. The density of a certain substance is inversely proportional to its volume; D. The larger the volume and density of different substances with the same mass
[Answer] B.
[Analysis] Density is a property of matter that does not change with changes in volume and mass. According to the density formula
, it can be seen that for different substances with equal volumes, the one with greater mass has a greater density; for different substances with equal masses, the one with greater volume has a smaller density.
A: The density of the same substance remains unchanged and does not change with the mass, so A is wrong.
B: According to the density formula
, it can be seen that for different substances per unit volume, the one with greater mass has greater density, so B is correct.
C: The density of the same substance remains unchanged and does not change with the volume, so C is wrong.
D: According to the density formula
, it can be seen that for different substances per unit mass, the one with a larger volume has a smaller density, so D is wrong. The answer is B.
7. Which of the following explanations about mechanical phenomena is correct ( ).
A. The ball falls faster and faster in the air because force can change the motion state of the object;
B. When a person pushes the cart hard, the cart does not move because the pushing force is less than the friction force;
C. The child slides down the slide on his own because he is affected by inertia;
D. The stationary electric light on the classroom ceiling is acted upon by a non- balancing force
[Answer] A.
[Analysis] A: The ball falls faster and faster in the air because the ball is affected by gravity, and force can change the motion state of the object. So statement A is correct.
B: When a person pushes the cart hard, the push force and friction force of the person are a pair of balanced forces, and the resultant force is zero, so the cart does not move. So statement B is wrong.
C: The child slides down the slide on his own because he is affected by gravity. So statement C is wrong.
D: The stationary electric light on the ceiling of the classroom is affected by gravity and the pulling force of the wire. The pulling force of the wire on the electric lamp and the gravity of the electric lamp. The two forces are equal in magnitude, opposite in direction, act on the same straight line, and act on the same object. This is consistent with The condition for the balance of two forces is a pair of balanced forces. Therefore statement D is wrong. Therefore choose A.
8. As shown in the picture, in order to explore the factors related to the size of kinetic energy, a student designed an experiment of "ball hitting a block", releasing the stationary wooden ball and observing the distance the block was pushed. What is said about this experiment , the incorrect one is ( ).
A. The design idea of this experiment is to use the conversion method, using the distance moved by the object to represent the size of the kinetic energy;
B. During the falling process of the ball, the gravitational potential energy decreases and the kinetic energy increases;
C. Replace the wooden ball with an iron ball of the same size and repeat the experiment. It is found that the distance the object is pushed increases, indicating that the greater the mass, the greater the kinetic energy;
D. The purpose of releasing the wooden ball from different heights and comparing the distance the object is pushed is to explore the relationship between kinetic energy and height
[Answer] D.
[Analysis] A, C: In the experiment, the kinetic energy of the small ball was compared by observing the distance the object was pushed on the same horizontal plane, so A is correct.
replaced the wooden ball with an iron ball of the same size, repeated the experiment, and found that the distance the object was pushed increased, indicating that the greater the mass, the greater the kinetic energy, so C is correct.
B: During the falling process of the ball, the height decreases, the gravitational potential energy decreases, the speed increases, and the kinetic energy increases, so B is correct.
D: Factors affecting the size of kinetic energy: mass, speed. It has nothing to do with the height of the object, so D is wrong. So choose D.
9. Which of the following statements about the phenomenon is correct ( ).
A. When the rubber rod rubs against the fur, the rubber rod is negatively charged because the friction generates electric charges;
B. Compared with trains, car surfaces are more likely to absorb dust;
C. Negatively charged objects attract light and small balls, and the balls must be positively charged;
D. electroscope can not only test whether an object is charged, but also measure the amount of charge carried by the object
[Answer] B.
[Analysis] A. The rubber rod rubs against the fur. The rubber rod is negatively charged because generates electricity through friction and creates electric charge; this statement is wrong. Charge cannot be created, only transferred.
B. It is true that dust is more likely to attract to the surface of a car than a train. When the car surface rubs against the air, frictional electrification will occur. When the car is charged, light and small objects (dust) will be absorbed.
C． If a negatively charged object attracts a small ball, the ball must be positively charged; this statement is wrong. When a charged object is close to a light or small object, it will also be attracted if the light and small object is not charged.
D. An electroscope can not only test whether an object is charged, but can also measure the amount of charge an object carries; this statement is wrong. An electroscope is an instrument used to test whether and how much an object is charged (determined based on the opening angle), but it cannot measure the amount of electricity charged. The correct answer is B.
10. The picture is an alarm circuit used when infusion : the power supply voltage is constant, R is the fixed value resistor , the switch S is closed, and the sensor M attached to the needle mouth comes into contact with the liquid leaking from the needle mouth. Later, its resistance RM changes, causing the voltmeter to increase and trigger the alarm (not shown in the figure) to alarm, then M comes into contact with the liquid ( ).
A. The resistance RM of M becomes larger;
B. The total power consumed by the circuit becomes larger;
C. The product of the indications of the voltmeter and the ammeter remains unchanged;
D. The ratio of the readings of the voltmeter and the ammeter becomes larger
[Answer] B.
[Analysis] It can be seen from the circuit diagram that the fixed value resistor R and the sensor resistance M are connected in series. The voltmeter measures the voltage at both ends of R, and the ammeter measures the current in the circuit. From the meaning of the question, it can be seen that after M comes into contact with the liquid, the alarm will sound, and the voltmeter will As the indication of V increases, it can be seen from the variant U=IR of
that when the indication of voltage increases, the current in the circuit becomes larger, that is, the indication of the ammeter becomes larger, and the product of the voltmeter and the ammeter becomes larger, so C is wrong;
can be known from P=UI
that when the power supply voltage remains unchanged, the total power consumed by the circuit becomes larger, so B is correct;
can be known from
that the total resistance in the circuit becomes smaller, because the total resistance in the series circuit The resistance is equal to the sum of the voltages of each component, so the resistance RM of M becomes smaller, so A is wrong;
It can be seen from
that the ratio of the voltmeter V to the ammeter A is equal to the resistance of the fixed value resistor R, then the ratio of the voltmeter to the ammeter No change, so D is wrong; therefore B should be chosen.
11. Today's society has entered a highly developed electrical era, and people must firmly establish the awareness of safe electricity use. However, in some places, the phenomenon of privately connecting wires indiscriminately is quite serious, which can easily cause safety hazards. Which of the following practices does not comply with the principles of safe electricity use ( ).
A. The switch must be connected to the live wire, and the switch and the electrical appliances it controls must be connected in series;
B. The metal casing of household appliances must be grounded;
C. Wipe the desk lamp bulb that is on with a damp cloth;
D. When a fire is found in a household appliance or wire, the power must be cut off first before putting out the fire.
【Answer】C.
[Analysis] A: In household circuits, in order to ensure the safety of electricity use, the switch that controls the electrical appliances should be connected to the live wire; it complies with the principle of safe electricity use.
B: In household circuits, the metal casings of household appliances must be grounded to prevent electric shock due to leakage and comply with the principles of safe electricity use.
C: Wet cloth is an easily conductive object. When wiping a glowing incandescent lamp or fluorescent lamp with a wet cloth, it may easily cause electric shock to the human body. It does not comply with the principles of safe electricity use.
D: When you find a fire in a household appliance or wire, you must first cut off the power supply and then put out the fire; do not put out the fire with electricity to prevent electric shock; comply with the principles of safe use of electricity. The answer is C.
12. The reasonable explanation for the four pictures A, B, C and D in the picture is ( ).
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A | B | C | ding |
A． A: Current is obtained in the magnetic field; B. B: The switch is closed, and the small magnetic needle N pole will deflect to the right;
C. C: It is a device based on the principle of a generator; D. Ding: When the switch is closed, mechanical energy will be converted into electrical energy
[Answer] C.
[Analysis] A: This experiment is Oersted's experiment : When a current passes through the wire, the small magnetic needle deflects. The experimental phenomenon shows that there is a magnetic field around the current, that is, electromagnetism . This phenomenon is called magnetism of the current. Effect , option A is wrong.
B: Close the switch and energize the solenoid. The direction of the current in is "front up, back down". According to ampere rule , the left end of the solenoid is the N pole, and the magnetic field line starts from the N pole and passes through it. When the small magnetic needle is pointing to the left, the N pole of the small magnetic needle will deflect to the left. Option B is incorrect.
C: What this device demonstrates is that when a conductor cuts magnetic field lines and moves in a magnetic field, a current will be generated in the conductor. The ammeter outside is used to detect whether there is current in the circuit, so the experiment of this device Principles, as applied to the manufacture of generators, option C is correct.
D: The principle of motor is that the energized coil is forced to rotate in the magnetic field. In the device based on the motor principle, there is an external power supply that provides current to the conductor; option D is incorrect. So choose C.
13. The use of the following machinery or tools belongs to labor-saving lever ( ).
- claw hammer B. Chopsticks c. Bottle opener D. wheelbarrow
[Answer] ACD.
[Analysis] The fulcrum of the claw hammer is the contact point between the hammer and the wood block, the resistance point is at the nail position, the power point is at the hand position, the power distance is greater than the resistance distance, so it is a labor-saving lever;
The fulcrum of the chopsticks is at the upper end of the chopsticks, and the resistance point is at When chopsticks pick up food, the power point is at the hand position, and the resistance distance is greater than the power distance, so it is laborious lever ;
The fulcrum of the bottle opener is in the center of the bottle cap, the resistance point is at the edge of the bottle cap, and the power point is in the hand. position, so the power distance is greater than the resistance distance, so it is a labor-saving lever;
The fulcrum of the unicycle is the contact position between the wheel and the ground, the resistance point is the center of gravity of the goods on the vehicle, and the power point is at the position of the hand, so the power distance is greater than the resistance distance, which is labor-saving. lever. The correct answer is ACD.
14. Which of the following statements about simple machines is correct ( ).
A. fixed pulley can change the size of the force, but not the direction of the force;
B. Using pulley set not only saves effort but also saves power;
C. The more work a machine does, the higher its mechanical efficiency ;
D. The more powerful the machine, the faster it does work
[Answer] AD.
【Analysis】A. A fixed pulley can change the magnitude and direction of force; this statement is wrong. A fixed pulley can change the direction of a force but not its magnitude.
B. Using a pulley block not only saves effort but also saves work; this statement is wrong. Using a pulley block can save effort, but not work.
C． The more work a machine does, the higher its mechanical efficiency is. This statement is wrong. A simple machine does more work, but it does not mean that its efficiency is high.
D. The more powerful the machine, the faster it will do work; this statement is correct. Power is a physical quantity that describes how fast work is done. High power means fast work is done. The correct answer is AD.
15. In order to practice using the sliding rheostat and at the same time explore the laws of voltage and current in series circuits, an experimental group designed the circuit as shown in the figure. The resistance of the light bulb in this circuit always remains unchanged. When the switch S is closed and the slider of the sliding rheostat P slides to the left, the electric meter is within the safe range, then ( ).
A. The indication of the voltmeter becomes smaller; B. The sum of the indication of the voltmeter and becomes smaller;
C. The indication of the ammeter A becomes smaller; D. If the voltmeter is suddenly short-circuited, the small light bulb will light up
【Answer】 AC.
[Analysis] (1) When the slider P of the sliding rheostat is moved to the left, the resistance of the sliding rheostat connected to the circuit becomes larger, and the total resistance becomes larger. According to Ohm's law , it can be seen that the current in the circuit becomes smaller; that is, the current The number indicated becomes smaller, so C is correct;
(2) Since the resistance of the light bulb always remains unchanged, according to U=IR, it can be seen that the voltage at both ends of the bulb becomes smaller, that is, the number indicated by the voltmeter becomes smaller; therefore A is correct;
(3 ) From the voltage characteristics of the series circuit, it can be seen that the sum of the indications and indications is the power supply voltage. Since the power supply voltage remains unchanged, the sum of the indications and indications remains unchanged, so B is wrong;
(4) Since the voltmeter is connected in parallel with the light bulb, if the voltage If the meter is suddenly short-circuited, the light bulb will also be short-circuited, so the light bulb will not emit light; therefore D is wrong. So choose AC.
Volume II (non-choice questions, 52 points in total)
2. Fill in the blanks (1 point each, 6 points in total)
16. The picture shows the situation of an experimental group "measuring the average speed of the car", as shown in the picture As shown in the figure, the car starts to move in a straight line from position A to position B. The time it takes is 2s. The total distance traveled by the car from A to B is ________cm. The average speed of the car during this period is _______m/s.
[Answer] 80.0, 0.4.
[Analysis] From the figure, the minimum division value of the scale is 1cm.
The distance the car passes from A to B: s=90.0cm-10.0cm=80.0cm=0.800m; the running time of the car t=2s;
The average speed of the car:
;
, so the answer is: 80.0, 0.4.
17. Xiao Ming saw "clouds floating in the water and fish swimming above the clouds" by the calm lake. Xiao Ming saw that the "clouds" in the water were formed by light, and he saw that the "fish" in the water were formed by light.
【Answer】Reflection and refraction.
[Analysis] The "cloud" in the water is the image of sky clouds in the water, which is the reflection of light; the "fish" in the water is the refraction of light.
So the answer to this question is: reflection and refraction.
18. Many people like to hang their mobile phones on their chests, which is very detrimental to their health because the radiation emitted by their mobile phones can affect the heart. Mobile phones work using electric energy, which belongs to (optional "primary energy" or "secondary energy").
【Answer】 electromagnetic wave , secondary energy.
[Analysis] Mobile phones use electromagnetic waves to transmit information. Electromagnetic waves will have certain radiation effects on the human body, so they are harmful to health. Electric energy cannot be obtained directly from nature, but needs to consume other primary energy sources, so electric energy is secondary energy .
So the answer is: electromagnetic waves, secondary energy.
3. Drawing, experiment and exploration questions (this question has 4 questions in total, totaling 26 points)
19. (2 points) (1) Draw the refracted rays of the two incident rays emitted from point S in the figure after passing through the lens .
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[Analysis] The three special relationships of concave lens are different from convex lens . Except that the light passing through optical center does not change direction, the other two should be: light parallel to the main axis, and light after refraction by the concave lens. of anti The light ray passes through the focal point on the same side toward the extension line; the light ray directed toward the focal point on the opposite side is parallel to the main axis after being refracted by the lens. as the picture shows.
【Answer】As shown in the figure.
(2) (2 points) As shown in the figure, draw the symbols of switches and light bulbs in the dotted boxes to make them meet the requirements for safe electricity use.
[Analysis] When the switch controls the light bulb, it is connected in series with the light bulb. The live wire goes into the lamp holder through the switch, and the neutral wire goes directly into the lamp holder.
The live wire first enters the switch, and then is connected to the metal point on the top of the bulb; the neutral wire is directly connected to the spiral sleeve of the bulb. This makes it safer when replacing bulbs. As shown in the figure:
20. (8 points) (1) In order to facilitate observation, this experiment is best conducted in the environment (brighter/darker); in addition, a transparent glass plate is used instead of the plane mirror , although the image is not as good as the plane mirror It is clear, but you can also observe the image of chess piece A at the same time, cleverly solving the problem of determining the position and size of the image.
(2) Carefully move the B chess piece until it is the image of A. At this time, you can find the size of the image and the object; further observe the positions of the two chess pieces A and B on the white paper and find that the line connecting the image and the object is related to the glass. plate. The distance between the image and the object to the glass plate is equal.
(3) If there are two glass plates of 5mm thickness and 2mm thickness, it is better to choose mm thick glass plate for experiment; if you choose another glass plate, it will be difficult to determine the position of the image because of: phenomenon.
(4) When looking for the position of the image of chess piece A, your eyes should be on the side of the chess piece (A/B).
(5) Remove chess piece B, use white paper as a screen and place it at that position. Observe the white paper directly and find that there is no image on the white paper. It can be seen that the image is formed by a plane mirror.
(6) In order to confirm whether the above-mentioned imaging characteristics are reliable, which of the following actions do you think should be taken? .
A. Keep the positions of chess pieces A and B unchanged, and change the position of the glass plate multiple times for observation;
B. Keep the position of the glass plate unchanged, change the position of A several times, and perform the same operation as (2) above.
[Answer] (1) Darker; chess piece B; (2) Completely coincident; equal; vertical; equal; (3) 2; Both surfaces of the thick glass plate can be used as reflective surfaces, and two images will appear; (4) A; (5) virtual image ; (6) B.
[Analysis] (1) To facilitate observation, this experiment is best conducted in a darker environment; using a transparent glass plate instead of a plane mirror can observe the image of chess piece A as well as chess piece B, making it easier to determine the image. location and size.
(2) In the experiment, carefully move the B chess piece until it completely overlaps with the image of A. It can be found that the size of the image and the object are equal; the line connecting the image and the object is perpendicular to the glass plate. The distance between the image and the object to the glass plate is equal.
(3) Because both sides of the thick glass plate can be used as reflective surfaces, two images will appear, which will affect the experimental results. Therefore, a thin glass plate should be used, with a thickness of 2mm.
(4) Since the plane mirror forms a virtual image, when looking for the position of the image of chess piece A, the human eye should observe on the side of chess piece A.
(5) The white paper in this experiment is equivalent to a light screen. The light screen can only accept real images, not virtual images. Because the image formed by the flat mirror is a virtual image, the image of the chess piece will not appear on the white paper.
(6) One experiment is not representative. The same experimental plan should be repeated several times to avoid the contingency of experimental phenomena to ensure the correctness of the conclusion. Therefore, action B should be taken.
So the answer is: (1) darker; chess piece B; (2) completely coincident; equal; vertical; equal; (3) 2; both sides of the thick glass plate can be used as reflective surfaces, and two images will appear ; (4) A; (5) virtual image; (6) B.
21. (6 points) In the experiment of exploring "factors affecting the size of sliding friction":
(1) To measure the size of sliding friction, Xiao Ming placed the wooden block on a long horizontal wooden board, as shown in the figure, using The spring dynamometer pulls in the horizontal direction to make it move. At this time, the wooden block is subject to friction and pulling force.
(2) Add weights and continue the experiment. This is to explore the impact on the sliding friction force. Xiao Ming operated correctly and completed the experiment.
(3) Spring dynamometer is an important measuring equipment in this experiment. In the following exploration experiment, the spring dynamometer is also used in the textbook (fill in the letter).
A. Explore the working characteristics of the fixed pulley;
B. Explore the effects of stress;
C. Explore the effect of resistance on the movement of objects;
D. Explore what factors are related to the magnitude of kinetic energy.
[Answer] (1) Uniform straight line, equal; (2) Pressure size; (3) A.
[Analysis] (1) Only when an object is pulled in the horizontal direction does it move in a straight line at a constant speed, the object is acted upon by a balancing force in the horizontal direction. The friction force on the block is equal to the pulling force, so it makes it move in a straight line at a constant speed.
(2) When a weight is added, the pressure of the object on the support surface increases, while the force-bearing area remains unchanged. This is to explore the impact of the pressure on the sliding friction force.
A. To explore the working characteristics of the fixed pulley, it is necessary to compare the force used to lift the object using the fixed pulley and the force used to directly lift the object without using the fixed pulley, so a spring dynamometer is used to measure the force;
B. To explore the effect of pressure, according to the conversion method, the effect of pressure is reflected by the degree of depression of the pressed object, without the need for dynamometer ;
C. To explore the impact of resistance on the movement of objects, according to the conversion method, the size of the resistance is explained by the length of the movement distance, without the need for a dynamometer;
D. Explore what factors are related to the size of kinetic energy. According to the conversion method, the size of the motion is reflected by the distance an object with kinetic energy pushes another object with a smaller mass through. There is no need for a dynamometer; so choose A.
The answer is: (1) Uniform straight line, equal; (2) Pressure size; (3) A.
22. (8 points) Xiaohua used " voltammetry " to measure a fixed value resistor Rx with a resistance of about 5Ω. The laboratory has the following equipment for selection:
A. Two dry batteries ; B. One switch and several wires; C. Voltmeter (0-3~15V); D. Ammeter (0~0.6-3A) E. Sliding rheostat (0~10Ω); F. Sliding rheostat (0~100Ω).
(1) After Xiaohua completed the experimental circuit design, in order to operate smoothly and conveniently, in addition to A, B, C and D, Xiaohua also needs to select equipment (optional "E" or "F");
( 2) According to the designed experimental circuit requirements, please use stroke lines instead of wires to connect the last two wires in Figure A;
(3) As shown in Figure A, connect the circuit. Before closing the switch, in order to protect the circuit, the slider P of the sliding rheostat should slide to the end (optional "G" or "H");
(4) Xiaohua moves the slider P of the sliding rheostat after closing the switch. , it is found that the current indication is always zero, while the voltmeter has an indication but does not change. At this time, a fault in the circuit is (optional A, B, C or D);
A. The sliding rheostat is open; B. The sliding rheostat is short-circuited; C. The fixed value resistor Rx is open circuit; D. The fixed-value resistor Rx is short-circuited
(5). After troubleshooting, the current value is 0.40A, and the voltage value is as shown in Figure B. Then the fixed-value resistor Rx measured in this experiment is Ω.
[Answer] (1) E; (2) As shown in the figure; (3) G; (4) C; (5) 5.5.
[Analysis] (1) The sliding rheostat is used in the circuit to change the indications of the ammeter and voltmeter to achieve multiple measurements; when the resistance of the sliding rheostat is larger, the voltage shared by both ends is larger, and the fixed value resistor has two The voltage shared by the terminal is small. When the slider moves, the indication of the voltmeter changes little, which is not conducive to the measurement of the experimental results; therefore, a sliding rheostat (0~10Ω) should be used;
(2) The power supply voltage is 2 sections The dry battery is 3V, so the voltmeter range is 0-3V; the sliding rheostat adopts an upper and lower connection method, as shown in the figure:
(3) Before closing the switch, the resistance value of the sliding rheostat is adjusted to the maximum, that is, the slider moves to the G terminal ;
(4) After closing the switch, the ammeter has no indication, but the voltmeter has an indication, indicating that the parallel part of the voltmeter is open, that is, the fixed value resistor Rx is open; therefore, C is selected;
(5) The indication of the voltmeter is 2.2V , the current expressed number is 0.40A, and the fixed value resistance Rx measured by
is:
.
So the answer is: (1)E; (2) as shown in the picture; (3)G; (4)C; (5)5.5.
4. Comprehensive application questions (20 points)
23. (10 points) With the continuous growth of our country's economy, our national defense strength is also strengthening. Our country's first aircraft carrier " Liaoning " has been officially handed over.Calculation based on the main parameter values of a certain aircraft carrier : (g=10 N/kg, ρ seawater=1.03×103 kg/m3)
Main parameter values | |
The total mass of the aircraft carrier (including carrier-based aircraft ) | 6×107 kg |
The mass of each carrier-based aircraft | 5150 kg |
The total contact area between each carrier-based aircraft and the deck | 5000 cm2 |
The normal sailing speed of the aircraft carrier | 54 km/h |
The resistance experienced by the aircraft carrier when traveling at normal sailing speed | 3.6×108 N |
(1) Find the pressure of each carrier-based aircraft on the deck;
(2) Find the total gravity and buoyancy on the aircraft carrier;
(3) If the aircraft carrier sails from point A to point B at a constant speed at normal sailing speed, it has traveled 540 km . Find the power of the aircraft carrier's traction force during this process;
(4) If one of the carrier-based aircraft takes off, how much does the volume of seawater displaced by the aircraft carrier decrease?
[Analysis] (1) The pressure of carrier-based aircraft on the deck: F=G1=m1g=5150kg×10N/kg=5.15×104N,
The pressure of carrier-based aircraft on the deck: p=
=
=1.03×105Pa.
(2) The total gravity of the aircraft carrier: G2=m2g=6×107kg×10N/kg=6×108N.
is floating, so F floats=G2=6×108N.
(3) Because the aircraft carrier is traveling at a constant speed, according to the two-force balance, we can get: F pull = f = 3.6 × 108N,
The power of the traction force: P = F pull v = 3.6 × 108N/kg ×
m/s = 5.4 × 109W .
(4) The buoyancy force on the aircraft carrier before and after the carrier-based aircraft takes off: F float = ρ liquid gV row, F float 1 = G2-G1 = ρ liquid gV row 1,
According to Archimedes’ principle, we can get: △V= V row-V row 1=
-
=
=
=5m3.
Answer: (1) The pressure of each carrier-based aircraft on the deck is 1.03×105Pa; (2) The total gravity and buoyancy of the aircraft carrier are both 6×108N; (3) The traction power of the aircraft carrier during travel is 5.4× 109W; (4) The volume of sea water displaced by the aircraft carrier has been reduced by 5m3.
24. (10 points) When Xiaoxuan returned to her hometown, it was very cold. She found that she needed to use a " bathroom heater " to take a bath, as shown in Figure 1. This "bath heater" has three functions: lighting, hair drying and heating. The lighting lamp L1 and the hair dryer (represented by
) can be controlled individually. The heating lamp L2 can only work after the hair dryer is started, as shown in the picture of the "bath heater" Simplified circuit diagram (Figure 2) and nameplate.
rated voltage | 220V | |
lighting lamp | rated power | 40W |
heating lamp | rated power | 500W |
Hair dryer | Rated power | 50W |
Ask: (1) What is the resistance of lighting lamp L1 when it is working normally?
(2) What is the current through the heating lamp L2 during normal operation?
(3) Usually, only the heating lamp L2 is turned on 10 minutes before washing to preheat the bathroom. How much power does the circuit consume during these 10 minutes?
(4) Xiaoxuan accidentally sprayed the bathroom heater with water while taking a bath. What harm will happen?
[Analysis] (1) It can be obtained from
. The resistance of the lighting lamp L1 when working normally:
;
(2) It can be obtained from P=UI. The current passing through the heating lamp L2 during normal operation:
;
(3) only When the heating lamp L2 is turned on for heating, the hair dryer will also work together with the heating lamp L2. According to
, the power consumed by the circuit in these 10 minutes is: W = (P2 + PM) t = (500W + 50W) × 10 × 60s = 3.3×105J;
(4) Spraying the bathroom heater with water during operation may cause dangers such as power short circuit.
[Answer] (1) The resistance of the lighting lamp L1 is 1210Ω when it is working normally; (2) The current through the heating lamp L2 is 2.27A when it is working normally; (3) The power consumed by the circuit in these 10 minutes is 3.3×105J; ( 4) Spraying the bathroom heater with water while working may cause dangers such as power short circuit.
