I want doc 2006 physics test, electricity.

Fill in the blanks

Shijiazhuang (2006) No.26. On the "sauna day" in summer, air conditioners and electric fans in residents' homes can't be idle, which leads to frequent circuit fires. The fire engine roared out with a siren and rushed to the scene of the fire. The investigation found that the cause of the fire was the same: the overload of the wire made the metal wire inside the wire heat up and ignited the insulation outside. According to the knowledge of physics, the answer is:

(1) "Overload" refers to the overload in the circuit (choose "current" or "resistance").

(2) The theoretical basis of fire is

(3) Please suggest what measures should be taken to prevent this fire.

Answer: (1) Currently

(2) The greater the current, the more heat will be generated according to Joule's law Q=I2Rt.

(3) high-power electrical appliances are used alternately; Replace the thicker transmission line according to the electrical power; Do a good job of circuit cooling.

(Taiyuan, 2006) 18. Electrical energy is transmitted to electrical appliances through power lines. In a DC circuit, the total resistance of the power line is 0.4 Ω, the electric power supplied to the electrical appliance is 40kW, the voltage is 800V, and the total current in the circuit is 50 A. If the original power line is replaced by a superconducting cable below the critical temperature (the resistance is zero), lossless power transmission can be realized.

(Taiyuan, 2006) 15. An electric energy meter is an instrument for measuring electric energy. The electric energy recorded by Xiao Ning at the beginning of the month is 4567.8 kw·h, and the figure at the end of the month is shown in Figure 5. His home is 70kW h this month.

(Jining City Curriculum Reform Area, 2006) Of the two methods of using the pencil shown in Figure 1, the correct one is _ _ B _.

(Jining City Curriculum Reform Zone in 2006) Property staff came to Li Ming's house to collect electricity. He observed the situation of Li Ming's electric energy meter, as shown in Figure 3. Then he found from the record book that the reading of the electric energy meter last month was 8 1 1.6 kwh. If charged at 0.5 yuan/kWh, the Li family will pay __60__ yuan for electricity this month. The total power of electrical appliances used by Li Ming's family at the same time shall not exceed1100 W.

Suqian (2006) 18. With the improvement of living standards, some high-tech achievements have gradually entered people's lives. The picture shows a solar street lamp. What information can you get from its description (just write three articles)?

Description of solar street lamp Re-TZ 13 1, solar cell: 40W2, light source: high-efficiency energy-saving lamp 3, system voltage: 12V4, continuous rain: 3~5 days 5, ambient temperature: -20℃ ~+70℃ 6, lighting time:/kl.

① ;

② ;

③ ;

(4) The essence of lamp work is to finally convert solar energy into.

Answer: ① Maximum output power of solar cell: 40W ② The bulb used is high-efficiency energy-saving lamp ③ The power supply voltage is 12V (it can work for 3-5 days in continuous rainy days; The ambient temperature is between -20℃ and +70℃; The continuous lighting time is 12 hours) Description: Name any three items and get 3 points.

④ Description of light energy (internal energy): Light energy, internal energy, light energy and internal energy are all correct.

Huzhou City (2006) Zhang Yu has a 34-inch color TV, which has a power of 500 watts when playing programs normally and 5 watts when standby (without turning off the power supply). On average, she spends 1/4 hours in the program every day, and another 3/4 hours in the standby state. Then the color TV consumes _ _ _ _ Joules every day on average, and cutting off the power supply can save _ _ _ _ Joules.

(Leshan City, 2006) No.59. Compared with ordinary magnets, electromagnets have the outstanding advantages of _ _ _ _ _ _ _ _ _ _ (just write one). Electromagnets are widely used in production and life, among which _ _ _ _ _ _ _ _ _ is used in electric furnaces, electric bells and electric lights.

Answer: Whether there is magnetism (strength or direction) can control the bell.

The nameplate of BCD- 195k refrigerator (Chongqing Curriculum Reform Zone in 2006) has the words "input data such as input voltage 220V, power consumption 0.7 kW h/24h, total power 120W". The data of "power consumption 0.7 kW h/24h" means that the electric energy consumed by the refrigerator in normal use for 24 hours is. If calculated according to the total input power 120 W, the power consumption is kW·h after working for 24 hours, which is quite different from the relevant data provided on the nameplate of the refrigerator. This is because of the refrigerator.

(Nantong City Curriculum Reform Zone in 2006) 18. An electric furnace has a resistance of 48.4 W, works in a circuit with a voltage of 220V V, and its power is _ _ _ _ W. When the electric furnace wire works, it turns red when heated, but the wire connecting the electric furnace wire is not very hot. The reason is _ _ _ _ _ _.

(Nantong City Curriculum Reform Zone in 2006) On March 1 2006, China began to implement the new energy efficiency standard for color TVs, stipulating that color TVs with standby power higher than 9W cannot enter the market. Xiao Ming wants to know whether the color TV at home meets the new energy efficiency standards. He connected the 100W light bulb to the circuit alone, and observed that the electric energy meter lmin turned five times. Then he connected the color TV to the circuit alone and was in a standby state. The watt-hour meter turns twice in 5 minutes, and it can be judged that the standby power of the color TV is _ _ _ W. If the standby time is calculated as 20 hours every day, the electricity consumed by Xiaoming's family every month (calculated as 30 days) due to the standby time of the color TV is about _ _ _ _ _ _ _ kW h. 。

(Yancheng, 2006) As shown in the figure, the total power of household appliances in Xiaoming's house cannot exceed W. When Xiaoming's house has only one lamp and the turntable just turns five times in three minutes, the electric energy consumed by the bulb is J, and its electric power is W. 。

An electric kettle in Huanggang City (2006), the nameplate parameters are as follows: rated voltage 220V, fuzzy rated power, thermal efficiency 90%. Under normal working conditions, it takes 5 minutes to boil a full pot of water, and the heat absorbed by the water is 1 18800J. At this time, the electric energy consumed by the hot water kettle is _ _ _ _ _ J, its rated power is _ _ _ _ _ _ W, and its resistance is _ _ _ _ _ _ _ Ω. If the actual voltage is 198V, the current through the electric kettle is _ _ _ _ A, and the heat generated by the electric kettle within 1min _ _ _ _ _ _ _ _ _ j (assuming that the resistance does not change with the temperature).

(Jiangxi Province in 2006) As shown in Figure 6, it is a five-hole socket commonly used in household circuits, in which hole A should be connected, hole B should be connected, and hole C should be connected.

(Wuxi, 2006) In March this year, China's color TV energy efficiency standards were formally implemented. The newly promulgated energy efficiency standard of color TV clearly stipulates that the standby power of color TV should not exceed 9W. It is estimated that after the implementation of this standard 10 year, the national cumulative power saving will be 3.772×108 kw h. In the process of using color TV, please put forward two reasonable suggestions on how to reduce the power consumption of color TV.

( 1) ;

(2) 。

(Wuxi, 2006) The voltage of the household circuit is V. In the household circuit, one end of the switch controlling the lamp is connected to the lamp, and the other end is connected to the wire.

(Shijiazhuang, 2006) 25. As shown in fig. 8, the power supply is composed of two new dry batteries connected in series, with a resistance of R = 20Ω, and the lamp L is marked with the words "6V 3.6W". After the switch S is closed, the current in the series circuit is A, the voltage across R is V, and the power consumed by the lamp L is W..

(Shandong Province, 2006) 18. Lily bought an air conditioner at her classmate's house yesterday. She installed it in the morning and turned it on. The air conditioner works normally. But at night, when lighting bulbs, microwave ovens and other electrical appliances are working normally, the air conditioner is turned on, but the fuse in the circuit is blown. The reason for the excessive current in the circuit is _ _ _ _ _.

(Hebei province in 2006) 13. For the circuit shown in Figure 5, after the switch S is closed, the indicator number of the ammeter (fill in "bigger", "smaller" or "unchanged"); If the current indicator changes by 0. 1A, the resistance r = ω. (Power supply voltage remains unchanged)

(Hebei Province Curriculum Reform 2006) 27 pages. Refrigerator brings a lot of convenience to our life. The above table is the main technical parameters of a refrigerator. Please answer the following questions:

( 1) _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

(2) The electric energy consumed by the refrigerator in one month (calculated by 30 days) is about _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ km h;

(3) The refrigerator absorbs heat rapidly by using the refrigerant _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _, thus reducing the temperature in the refrigerator;

(4) There are _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.

Total effective volume 198 liter

The total input power is100W.

Rated voltage 220 volts

The freezing capacity is 10 kg/24h.

The power consumption is 0.6 kW hour /24 hours.

Frequency 50Hz

(Pudong, Shanghai, 2006) The electric energy meter is used to measure the electric energy consumed by users. As shown in Figure 5, if the indicated value of the electric energy meter is different from that in the figure, the electricity consumed by the user during this period is _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Dalian (2006) 6. In the household circuit, several working household appliances are connected by _ _ _ _ _. Increase the number of household appliances at work, and the rotary speed of the electric energy meter will change by _ _ _ _ _.

(Huaian, 2006) 17. The easiest way to distinguish between two old and new incandescent bulbs with exactly the same specifications and models is to observe the glass wall of the bulb and the inner wall of the old bulb _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.

A: The blackening temperature makes the polymer move faster and smaller.

The picture on the right shows the main parameters of the rice cooker. Therefore, working at rated voltage, the current through the rice cooker is about a, the rice cooker works normally for 0.5h, and the power consumption is kW h. ..

Rated voltage 220 volts

Rated power 900W

Rated frequency 50Hz

Rated volume 5L

Shenzhen, 2006, 24. As shown in Figure 9, the lamp L is marked with the words "6V 3W", and the switch S is closed. When the slider P moves to the A end, the ammeter pointer is 0.6A, and the lamp L emits light normally. Then the work done by the current flowing through L every minute is _ _ _ _ _ _ J. The maximum resistance of the sliding rheostat is _ _ _ _ _ _ _ Ω.

Second, multiple choice questions

(Jining City Curriculum Reform Zone in 2006) Zhu Qiu observed some phenomena while helping his mother cook in the kitchen, and explained them with the knowledge of physics. The incorrect explanation was (c).

A, sharpening the knife is to increase the pressure.

B, the pressure cooker cooks fast because the pressure increases and the boiling point rises.

C the "white smoke" emitted when the refrigerator is opened is the water vapor generated by the evaporation of vegetables and fruits in the refrigerator.

D, rice cookers with three-pin plug and three hole socket, in order to prevent electric shock accidents caused by pot leakage.

(Jining City Curriculum Reform Area in 2006) The nameplates of two ordinary lighting bulbs (A and B) are shown in Figure 4, and the correct one in the following statement is (D).

A. the actual power of lamp a must be 25W B. connect lamp b to 1 10V circuit, and its actual power is 50W.

C. When both lights are on normally, lamp B consumes more electric energy. When both lamps are lit normally, the filament resistance of lamp A is relatively high.

Dalian (2006) 24. (multiple choices) Connect a sliding rheostat to the power supply, and the power consumption is P. To make its power consumption half of the original, the measures that can be taken are [].

A. the power supply voltage is constant, and the resistance value is doubled.

B, the power supply voltage is constant, and the resistance value becomes half of the original.

C, the power supply voltage and resistance are reduced by half.

D, the power supply voltage is reduced by half, and the resistance value is doubled.

In Family Life (Laiwu City, 2006), the following estimates are in line with the facts.

A. The electric power of household color TV is about100 w.b. The desktop area is about 200cm2.

C. The water temperature of the bath water is about 70℃. D. When people stand on the ground with their feet, the pressure on the ground is about 1000Pa.

With the gradual improvement of people's living standards, the number of household appliances is increasing. In the home circuit, the following statement is correct.

Yes ()

The lamp is connected in parallel with the switch controlling it and in series with the socket.

B. When using the measuring pen, don't touch the metal body at the end of the pen with your hands.

C. One of the reasons for the excessive current in the circuit is that the total power of the electrical appliances used is too large.

D. When adding high-power electrical appliances, just replace the fuse that is thick enough.

(Lishui City Curriculum Reform Area in 2006) The fuse of the home circuit is blown, and the reason may be that

A. short circuit B. someone gets an electric shock C. the bulb filament is broken D. the zero line is open.

(Nantong City Curriculum Reform Area in 2006) Among the following graphic phenomena, the one that conforms to the safety of electricity consumption is

When the electrical appliance is on fire, cut off the power supply first, dry the wet clothes on the wires, and wipe the electrical appliance with a wet cloth. Household appliances are not grounded.

A B C D

In the four circuits shown in the figure, the power supply voltage is the same, and the order of the total power consumed by the circuits from large to small is as follows

A.a，B，C，D，B，D，C，B，a。

C.d，a，b，c，c，b，a，d

(Hangzhou, 2006) After learning about home circuits, students in a class installed four electric lights. What do you think is right?

A B C D

(Yancheng City, 2006) About the common sense of electricity consumption, the following statement is correct (A)

A the fuse in the fuse is broken and cannot be replaced by copper wire.

B when installing the knife switch, the power inlet can be connected to the upper two terminals or the lower two terminals.

C the wire is connected to the socket, and the live wire can be connected to the left jack or the right jack.

D when connecting the nut, the live wire can be connected to the metal plate or screw sleeve in the nut.

(Huanggang City, 2006) The following meet the requirements for safe electricity use:

(Nanjing 2006) In life, the following measures that do not conform to the safety of electricity use are ()

A. the metal shell of household appliances should be grounded.

B. the switch must be connected to the live wire.

C. When household appliances or wires are found to be on fire, the power supply must be cut off first, and then the fire is put out.

When someone gets an electric shock, you should immediately pull him away by hand.

Quzhou City, 2006. Due to the lack of scientific common sense, casualties occur from time to time. The following practice is correct.

A For household appliances with a metal shell, the grounding wire of the shell can be connected to the zero line of the power supply.

B. Don't touch the low-voltage charged body and stay away from the high-voltage charged body.

C. When diluting concentrated sulfuric acid, directly pour water into concentrated sulfuric acid.

D when the electrical equipment is on fire, use water to extinguish the fire first, and then cut off the power supply.

(Nanjing, 2006) In the circuit shown in Figure 8, the power supply voltage is constant, Rl is a constant resistance, and Rl is a sliding rheostat. When the switch S is closed, the sliding blade of the sliding rheostat moves from B to A ().

A. The indication of ammeter A becomes larger, and the ratio of voltmeter V2 to ammeter A becomes smaller.

The indication of ammeter A becomes larger, and the ratio of voltmeter V2 to ammeter A becomes smaller.

C the indication of voltmeter V 1 remains unchanged, and the total power consumed by the circuit increases.

D the indication of voltmeter V2 becomes smaller, and the total power consumed by the circuit changes.

As shown in the figure, when the switch S is closed, it is found that the electric lamp L is not lit. When C and D are tested with a pencil, both neon tubes glow. When testing points A and B, only the neon tube at point A glows. The fault may be

A.short circuit between live wire and neutral wire The filament of the electric lamp is broken.

(Ningbo, 2006) Xiaoming plugs the desk lamp into the socket. When he turned off the desk lamp switch, all the other lights in the room went out. The inspection found that the fuse was blown. The cause of this failure may be ()

A. short circuit of lamp holder B. short circuit of socket C. short circuit of plug D. short circuit of switch

(Zhejiang Province in 2006) In the experiment of measuring the electric power of small light bulbs, the circuits connected by four students in a class are shown in the figure, in which the correct connection is

(Wuxi, 2006) Sliding rheostat is a common electrical equipment. There is a sliding rheostat marked "10 12 1A" in the physics laboratory. Xiao Ming studied it and came to the following conclusion, of which the wrong one is ().

A The maximum resistance that this sliding rheostat can be connected to the circuit is 10 12.

B. When the current in the sliding rheostat does not exceed 1A, it can be used safely.

C when the voltage across the sliding rheostat does not exceed 10V, it can be used safely.

D. When the sliding rheostat is used safely, its maximum power consumption is 10w.

(Fuzhou, 2006) In the scenario shown in Figure 4, the following are in line with the safe operation of electricity consumption.

Suqian City (2006) When Xiaoming was doing his homework, he found the lights flickering. The reason may be that

A. The actual voltage of the light bulb has changed. B. The rated power of the light bulb has changed.

C. the rated voltage of the light bulb has changed. D. the light bulb is burnt out.

(Linyi City, 2006) The use of electric energy has brought a lot of convenience to people's production and life, but it will also bring harm to people if it is used improperly. The following practices may bring harm to people.

A. Please disconnect the power supply before replacing the light bulb or repairing the circuit.

B. the switch should be connected to the live wire.

C. three hole socket grounding wire shall ensure good grounding.

D. there is no suitable fuse for the time being. It can be replaced by thin steel wire in a short time.

(Taizhou, 2006) Xiaohua is going to participate in the toy racing competition. He uses the circuit shown in fig. 5 to select a motor with high energy conversion efficiency. Assuming that the voltage of the battery is constant, he first holds the rotating shaft of the motor by hand so that it does not rotate, then closes the switch and reads the reading of the ammeter as 2A. Then let go, when the motor rotates normally, the ammeter reads 0.6A, so when the toy motor rotates normally, the efficiency of converting electric energy into mechanical energy is

A.9 1% B.70% C.30% D.9%

(Taizhou, 2006) Electric energy meter is an instrument for measuring the power consumption of electrical appliances. Xiaohua wanted to check whether the revolutions per kilowatt hour marked on the dial of his watt-hour meter were accurate, so he connected the electrical appliance marked "220V 3A" to the circuit separately. After the electrical appliance works normally for 5 minutes, the dial of the watt-hour meter just rotates 1 10r, and the actual revolutions per kwh of the watt-hour meter should be

1500 r d 1200 r

Zhenjiang City (2006) 16, Xiaoming incandescent bulb filament burned out. His father put the broken filaments together and continued to use them. He found that the light bulb was brighter than usual because of the filament ().

A. the resistance decreases and the current increases. B. the resistance decreases and the current decreases.

C. the resistance increases and the current increases. D. the resistance increases and the current decreases.

Zhenjiang (2006) 18. The lamp Ll is marked with the words "8V 16W" and the lamp L2 is marked with the words "12V 36W". After the two lamps are connected in series, they are connected in a circuit with a voltage of U. In order to ensure that the two lamps are not damaged, the maximum voltage of U should be ().

12V c 16V d . 20v

Zhenjiang (2006) No.20. Xiaoming does his homework at night. He plugged the lamp into the socket beside the desk and turned off the lamp switch. In order to find out the cause of the fault, Xiao Ming plugged the desk lamp into other sockets and found that the desk lamp could shine normally. He inserted a test pencil into the socket hole beside the desk for inspection, and found that one of the holes could make the neon tube of the test pencil glow. The reason for the failure may be ().

A. the fuse on the incoming wire is blown. B. the incoming zero line is broken.

C. the socket beside the desk is disconnected from the neutral line d, and the socket beside the desk is disconnected from the live wire.

(Leshan City, 2006) No.25. When the household color TV works normally, the electric power is closest to B.

a . 1000 w b . 200 w c . 10W d . 1W

(Shaanxi Province Curriculum Reform Area in 2006) 6. The following statement about rice cookers is true (C)

A, when it works, metal surgery can not be grounded. B when it works, it converts internal energy into electric energy.

C, using heat generated by current to heat food D, and connecting with other household appliances in series when working.

(Wuhan, 2006) 9. In order to respond to the call of the central government to "mobilize the whole people to build a conservation-oriented society", Xiaoming put forward the following suggestions on saving electricity, some of which are unscientific

A. Please turn off the light when you leave the room. B. Replace the electric water heater at home with a solar water heater.

C. Use electronic high-efficiency energy-saving lamps D. Turn off the air conditioner at work, open the refrigerator door and lower the room temperature.

(Wuhan, 2006) 12. The following statement about the safe use of electricity is correct.

A. As long as the light doesn't work, you can clean it with a wet cloth.

B. As long as a thicker fuse is replaced, high-power electrical appliances can be connected to the circuit.

C connect the metal shell of household appliances to the ground wire to prevent electric shock.

D when you see someone get an electric shock, you should immediately pull him away by hand.

(Wuhan, 2006) 13. Xiao Ming wants to do the following experiment through the circuit diagram as shown in the figure. What do you think is not feasible?

A. verifying ohm's law

B. verifying Joule's law

C. measure the power consumed by the resistor R 1.

D. Confirm that the total voltage across the circuit is equal to the sum of the voltages across all parts of the circuit.

(Shandong Province, 2006) 9. If the TV, soldering iron and electric fan are all marked with the words "220V 60W" and all work at the same time under rated voltage, what is the most heat generated by the three electrical appliances?

A. TV sets B. electric fans C. electric irons D.

(Shandong Province, 2006) 12. Mr. Zhang's business trip coincides with the meter reading day, and his electric energy is shown in Figure 5 (A). When he came back from a business trip, he found a 60W desk lamp on at home, and all other appliances were turned off. Then, as shown in Figure 5 (B), Mr. Zhang has a long business trip.

A.b. 14.4 hours c.0.24 hours d.240 hours

Beijing (2006) 5. The following electrical appliances, using the thermal effect of current work is

A. motor B. electric fan C. refrigerator D. rice cooker

(Beijing, 2006). Among the four practices shown in Figure 4, those that meet the requirements for safe electricity use are

(Beijing, 2006) 17. There are four small light bulbs L 1, L2, L3 and L4, which are labeled as "12V 20W", "10W" and "6V 10W" respectively.

A. connect L 1 and L4 in series and access the circuit. Connect L2 and L4 in series and connect them into the circuit.

C. connect L 1 and L3 in series and access the circuit. Connect L2 and L3 in series and connect them into the circuit.

(Hebei Province in 2006) 10. As shown in Figure 4, the power supply voltage U= 18V, and the rated voltage of the small bulb L is 9V. When the slider P of the sliding rheostat moves to the midpoint, the small bulb L emits light normally; When the slider P moves to the extreme right, the actual power of the small bulb L is 6W. The rated power of the small bulb and the maximum resistance of the sliding rheostat are respectively

a . 13.5 w 6ωb . 6w 13.5ωc . 6w 12ωd . 13.5 w 12ω

(Hebei Province Curriculum Reform 2006) 22 pages. As shown in Figure 7, the power supply voltage U= 18V, and the rated voltage of the small bulb L is 9V. When the slider P of the sliding rheostat moves to the midpoint, the small bulb L emits light normally; When the slider moves to the extreme right, the actual power of the small bulb is 6W. The rated power of the small bulb and the maximum resistance of the sliding rheostat are respectively

a . 13.5 w 6ωb . 6w 12ωc . 6w 27ωd . 13.5 w 12ω

(Dalian, 2006) 14. The rated power of the following household appliances is close to 800W []

A. table lamp B. TV C. electric fan D. rice cooker

(Dalian, 2006) 18. Household appliances such as refrigerators, washing machines and electric heaters all use three-pin plugs, and their purpose is [].

A. save electric energy B. make household appliances get electric energy

C, prolong the service life of household appliances d, prevent electric shock accidents when the shell of household appliances is charged.

(Huaian, 2006) 5. Household appliances that work through the thermal effect of current are

A. rice cookers, washing machines, refrigerators and televisions

(Huaian, 2006) 10. The function of fuse in household circuit is

A. preventing electric shock B. stabilizing voltage C. measuring electric energy D. protecting circuit

Yichang (2006) 14. After the electric furnace is electrified, the wires of the electric furnace are red with heat, but the wires connected with the wires of the electric furnace are not so hot, because

A. the current passing through the electric furnace wire is very large. The current through the wire is very large.

C. the resistance of the electric furnace wire is small, and the heating power is small. D. the conductor resistance is small and the heating power is small.

(Huanggang City, 2006) 5. In the household electricity, meet the requirements of electricity are

(Shenzhen in 2006) 9. The following common sense about household electricity consumption is correct.

A, the metal shell of household appliances need not be grounded.

B standing on a dry wooden bench and touching two wires at the same time won't get an electric shock.

C, found someone get an electric shock, should cut off the power supply as soon as possible.

D, wet hands can directly switch on and off electrical appliances.

Third, painting, experiment and scientific inquiry.

The experimental equipment (Laiwu City, 2006) for measuring the rated power of a small light bulb is shown in Figure 8. The small light bulb is marked with the word "3.8V" and its resistance is about10Ω.

(1) Please connect the equipment in Figure 8 into an experimental circuit by pressing wires instead of wires (wires should not cross).

(2) Xiaogang properly connected the circuit and closed the switch. No matter how to adjust the sliding rheostat bulb, it didn't light up. So Xiaogang put forward the following conjecture:

Maybe the filament is broken.

B.maybe the light bulb is short-circuited.

C. Maybe the rheostat is on.

According to the readings of ammeter and voltmeter, you can judge which guess is correct (neither ammeter nor voltmeter is faulty). The following table gives several possible situations of ammeter and voltmeter. Please decide which guess is correct in each case and fill in its serial number in the corresponding space.

Judging results of ammeter and voltmeter

The indicator is not zero. The indicator is zero.

The indicator is zero, and the indicator is not zero.

The indicator is zero. The indicator is zero.

(3) After troubleshooting, Xiaogang adjusted the sliding rheostat to make the bulb glow normally. The current representation at this time is as shown in Figure 9, so the current flowing through the light bulb is _ _ _ _ _ _ _ _ _ _ _ A, and the rated power of the light bulb is _ _ _ _ _ _ _ _ _ _ _ _.

Judging results of ammeter and voltmeter

Indicator is not zero, indicator is zero, b

The indicator is zero and the indicator is not zero.

The indicator is zero, and the indicator is zero C.

Answer: (1) Omit (2)

(3)0.36、 1.368

In the experiment of "measuring the electric power of light bulb", it is known that the power supply is two lead batteries, the rated voltage of light bulb is 2.5V, the resistance is about 10W, and the sliding rheostat is marked with the word "20WLA". Some circuits connected by a classmate are shown in figure A. 。

(1) There is an error in the circuit connected by this classmate. Please mark the errors with "×".

(2) After the error is corrected, please completely connect the circuit in Figure A with a scribe instead of a wire.

(3) When the switch is closed and the slider of the rheostat moves to a certain position, the voltage is expressed as 2.5V, and the current is shown in Figure B, so the current in the small light bulb is ______A, and the rated power of the small light bulb is _ _ _ _ _ _ _ _ _.

(4) After another student connected the circuit and closed the switch, he found that the small light bulb turned on first and then went out. What do you think of the possible problems with his connection circuit? _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.

Before the college entrance examination in Jiangxi in 2006, my father bought a new air conditioner for Xiao Liang, which provided a comfortable study and living environment at home. After installation, all household appliances will stop working as soon as they are used. After inspection, it was found that the fuse was blown. (l) Try to analyze the cause of fuse blowing. (2) How to improve the household circuit to make all household appliances work normally after connecting the air conditioner?

(Yancheng, 2006) Using the experimental equipment as shown in the figure, the electric power of a small bulb with rated voltage of 6V was measured. Known sliding rheostat is marked with the words "12Ω1a", and the power supply voltage is unchanged.

The experimental steps are as follows:

A. connect the circuit. Draw a line on Figure A to complete the circuit for measuring the electric power of small bulbs. When the slider P needs to move to the right, the small light bulb turns dark.

B. After the circuit is connected, all the resistors of the sliding rheostat should be connected to the circuit. First, move the slider P to the bottom, and then close the switch S. At this time, the voltage is expressed as 4.2V, and the corresponding current is shown in Figure B. 。

C. adjust the slider. When P moves to the midpoint of ab, the light bulb just shines normally.

D. continue to adjust the slider. When P moves to another point, the light bulb is on the bright side, and the values of voltmeter and ammeter are 6.5V and 0.52A respectively, which are recorded in the table below.

Number of experiments /V current /A brightness power /W

1 4.2 is dark.

2 6.0 normal

3 6.5 0.52 Good side 3.38

Please fill in all the data in the blank space of the above table, and then analyze the information in the table. The conclusion is (just write two):?

;

.

The experiment of measuring the electric power of small bulb (Jiangxi Province in 2006) shows that the power supply voltage is 6V, the rated voltage of small bulb is 2.5V, and the resistance of small bulb is about 10.