A, fill in the blanks
(2006 Shijiazhuang City) 26. summer continued "sauna days", the residents of the home air conditioning, fans are not idle, resulting in circuit fires from time to time, the fire alarm calls, the fire truck pulling the siren whistling out, rushed to the scene of the fire, the investigation found that the cause of the fire was the same: overloading the wires so that the metal conductor inside the wire heat ignited the outer insulation. The cause of the fire is the same: overloaded wires so that the wire inside the metal wire heat ignited the outside of the insulating skin. According to the learned knowledge of physics answer:
(1) "overload" refers to the circuit is too large (fill in "current" or "resistance").
(2) The theory behind the fire is
(3) Suggest a measure that should be taken to prevent the fire.
Answer: (1) Current
(2) The higher the current, the more heat is generated according to Joule's law Q=I2Rt
(3) Cross-use of high-powered electrical appliances; switch to thicker transmission wires according to the power of the electrical appliances; and do a good job of dissipating heat from the circuit.
(2006 Taiyuan City) 18. Electricity is delivered to appliances through transmission lines. A DC circuit, the total resistance of the transmission line is 0.4Ω, the electric power supplied to the appliance is 40kW, the voltage is 800V, the total current in the circuit is 50A. If the critical temperature of the superconducting cables (resistance is zero) instead of the original transmission line, lossless power transmission can be realized. Under the condition of keeping the power and voltage supplied to the appliances unchanged, the saving of electric power is 1kW
(2006 Taiyuan City) 15. The energy meter is a meter for measuring electricity. Xiaoning students home at the beginning of the month to record the number of electrical energy is 4567.8kW - h, the end of the month, as shown in Figure 5, his home this month with 70kW - h.
(2006 Jining City, Jining classroom reform area) in Figure 1 shows the A, B two ways to use the stylus, the correct is ___ B _ .
(2006 Jining City class reform district) property staff came to Li Ming's home to collect the electricity bill, he observed Li Ming's home energy meter as shown in Figure 3. Then from the record book to find out last month's meter is 811.6kWh. If according to the 0.5 yuan / kWh billing, Li Ming's home this month should be paid __60__ yuan of electricity. Li Ming's home at the same time the total power of electrical appliances shall not exceed 1100 W.
(2006 Suqian City) 18. With the improvement of living standards, some high-tech achievements have gradually come into people's lives. As shown in the figure is a solar street lamp, you can get from its related instructions in what information (write out three can)?
Solar street lamp description RE-TZ131, solar cells: 40W2, light source: energy efficient lamps 3, the system voltage: 12V4, continuous rain: 3 ~ 5 days 5, ambient temperature: -20 ℃ ~ +70 ℃ 6, the lighting time: 12 hours
①;
;
;
② ;
③ ;
④The essence of the work of the lamp is to convert solar energy eventually into .
Answer: ① solar cell maximum output power: 40W ② the use of light bulbs for high-efficiency energy-saving lamps ③ power supply voltage is 12V (continuous cloudy and rainy can work for 3 ~ 5 days; ambient temperature between -20 ℃ ~ +70 ℃; 12 hours of continuous lighting time) Description: Name any three can be scored 3 points
④ light energy (internal energy) Explanation: light energy, internal energy, light energy and internal energy are correct
(2006 Huzhou City) Zhang Yu students have a 34-inch color TV at home, in the normal playback of the program when the power is 500 watts, and standby (without cutting off the power supply) when the power of the 5 watts, an average of 1/4 of the time each day in the insertion of the program, the other 3/4 of the time in standby mode. Then the color TV consumes an average of ___▲___ joules of electricity per day, of which ___▲___ joules can be saved by cutting off the power.
(2006 Leshan City) 59. The outstanding advantage of electromagnets over ordinary magnets is ________________(write one can). Electromagnets in production and life in many applications, in the electric stove, electric bells, electric lamps, the use of electromagnets is _____________
Answer: the presence or absence of magnetism (strength or direction) can be controlled Electric bells
(2006 Chongqing Municipal Curriculum Reform District) BCD-195K refrigerator nameplate has "Input voltage 220V, power consumption 0.7 kW-h/24h, total input power 120W" and other data. Which "power consumption o.7kW - h / 24h" the meaning of this data is: the refrigerator normal use of 24h power consumption for ． According to the total power of 120 W and work for 24 h, the power consumption is kW-h, this calculation result and the refrigerator nameplate provides the relevant data on the difference is large, this is due to the refrigerator has the characteristics of the work of the cause.
(2006 Nantong City, class reform area) 18. an electric stove resistance of 48.4 W, connected to the voltage of 220 V circuit work, its power is _____ W. The electric stove wire work hot red, while connecting the wire of the electric stove wire is not very hot, the reason is that ______________________________________________.
(2006 Nantong City, class reform area) March 1, 2006, China began to implement the new standard of energy efficiency of color TVs, the standby power higher than 9W color TVs can not enter the market sales. Xiaoming would like to know whether the color TV at home in line with the new energy-efficiency standards, he will be 100W bulb alone into the circuit, observe the power meter lmin turned 5: then let the color TV alone into the circuit and in standby mode, the power meter 5min turned 2, which determines that the standby power of the color TV for _____W. If standby every day according to the calculation of the 20h, Xiaoming's home every month (according to the calculation of the 30 days) due to the color TV Standby power consumption is __________kW-h.
(2006 Yancheng City) Xiaoming home power meter shown in the figure, the total power of home appliances can not be more than W. When Xiaoming's home is only a lamp work, 3min turntable exactly 5 turns, the light bulb consumes electricity is J, its electric power is W.
(2006) (Huanggang City) an electric kettle, the nameplate part of the parameters are as follows: rated voltage 220V, rated power ambiguous, thermal efficiency of 90%. Under normal operating conditions boiling a full pot of water takes 5min, the heat absorbed by the water is 118800J, at this time, the kettle consumes electricity for _______J, its rated power is _________w, the resistance is _______Ω. If the actual voltage is 198V, the current through the electric kettle is _______A, and the heat produced by the electric kettle in 1min is ________J. (Assuming that the resistance does not change with the temperature)
(2006 Jiangxi Province) Figure 6 shows a five-hole socket commonly used in household circuits, where hole A should be connected to the line, hole B should be connected to the line, hole C should be connected to the line.
(2006 Wuxi City) In March this year, China's color TV energy efficiency standards were formally implemented. The newly promulgated color TV energy-efficiency standards clearly stipulate that the standby power of color TV shall not exceed 9W, it is expected that after the implementation of the standard 10 years, the country can accumulate power savings of 3.772 × 108kW-h. In the process of using color TV, on how to reduce the color TV power consumption, please put forward two rationalization proposals.
(1) ;
(2) .
(2006, Wuxi City) The voltage of a household circuit is V. In a household circuit, the switch that controls the light is connected to the light at one end and should be connected to the line at the other end.
(2006 Shijiazhuang City) 25. As shown in Figure 8, the power supply has two new dry-cell batteries in series, resistance R = 20 Ω, the lamp L is labeled "6V 3.6W", after closing the switch S, the current in the series circuit is A, the voltage at the ends of R is V, the lamp L consumes the power of W.
(2006 Shandong Province) 18. p>(2006 Shandong Province) 18. Yesterday Lili students home to buy an air conditioner, the morning after the installation opened, the air conditioner works normally. But in the evening, in the lighting bulbs, microwave ovens and other appliances work normally and then open the air conditioning, the circuit fuse blew. The reason for the excessive current in the circuit is ＿＿＿＿＿.
(2006 Hebei Province) 13. As shown in Figure 5, the circuit, switch S closed, the ammeter (fill in the "bigger", "smaller" or "unchanged") If the current changed 0.1A, then the resistance R = Ω. (The supply voltage remains unchanged)
(2006 Hebei Province, the reform of the class) 27. refrigerator to bring us a lot of convenience in our lives, the table above is the main technical parameters of a model refrigerator. Please answer the following questions:
(1) the refrigerator plug should be ____________________ (fill in "two-pronged plug" or "three-pronged plug");
(2) the refrigerator for a month (calculated on the basis of 30 days) consumes about 30% of the electrical energy. Calculation) consumes about _________________________KM-h of electricity;
(3) the refrigerator is the use of cold-causing substances to rapidly ________________________ absorb heat, so that the temperature inside the refrigerator is lowered;
(4) activated carbon has a ___________________________________ properties and is commonly used as a deodorizer in refrigerators.
Total effective volume 198L
Total output power 100W
Rated voltage 220V
Freezing capacity 10kg/24h
Electricity consumption 0.6kw. h/24h
Frequency 50Hz
(2006, Shanghai, Pudong) Electricity meter is used to measure the user's Consumption of electricity meter is used to measure the energy consumption of the user, as shown in Figure 5, if the energy meter display from the value in the figure to , then this period of time the user's consumption of electricity is ________ degrees, the energy can be a labeled "220V 40W" incandescent lamps work for ______ hours of continuous normal work.
(2006 Dalian) 6. In a household circuit, several working household appliances are ________ connected. By increasing the number of working household appliances, the speed of rotation of the energy meter dial changes ________.
(2006 Huaian City) 17. Distinguish between specifications, models identical to the two old and new incandescent light bulbs, the simplest way is to observe the glass wall of the bulb, the old bulb's inner wall _______, with the points of view of the molecules to explain the reason for _____________, after a long period of time when the bulb is used, normal use, compared with the rated power, the actual power ___________(choose "bigger", "smaller" or "unchanged").
Answer: blackened temperature high molecular movement faster smaller
(2006 Tai'an City, non-curriculum reform area) the right table for the main parameters of a rice cooker. It can be seen that, working at the rated voltage, the current through the rice cooker is about A. The electrical energy consumed by the rice cooker in normal operation for 0.5h is kW-h.
Rated Voltage 220V
Rated Power 900W
Rated Frequency 50Hz
Rated Volume 5L
(2006 Shenzhen City)
(24)
(2006 Shenzhen City)After the light is shown in Fig.9, the lamp L is labeled with a "light" and the lamp L is labeled with a "light" and the lamp L is labeled with a "light" and a "light". , the lamp L is labeled "6V 3W", the switch S closed, slide P moved to the a end, the ammeter shows 0.6A, the lamp L normal light. The work done by the current through L is ____________J per minute. The maximum resistance of the sliding varistor is ____________Ω.
Two, multiple-choice questions
(2006 Jining City, Jining classroom) Qiuzhu students in the kitchen to help his mother cook observed some phenomena, and with the physical knowledge of the explanations, which is not the correct explanation is (C)
A, sharpening knives, in order to increase the pressure
B, pressure cooker cooking fast, because the pressure increases, the boiling point rises
C, open the refrigerator when the "white smoke", is the refrigerator vegetables and fruits, such as the evaporation of water vapor
D, rice cooker with a three-pronged plug and three-hole plug. Three-pronged plug and three-hole socket, in order to prevent the pot leakage caused by electrocution accident
(2006 Jining City, Jining classroom district) A, B two ordinary lighting bulbs nameplate shown in Figure 4, the following statements are correct ( D )
A. A lamp of the actual power must be 25W B. B lamp into the 110V circuit, it is the actual power of 50W
C. the two lamps are normal light, lamp B consumes more power D. the two lamps are normal light, lamp A filament resistance is larger
(2006 Dalian City) 24. (Multiple choice) will be a sliding rheostat connected to the power supply, the power consumed by P. To make the power consumed by the power of half of the original, you can take the measures are [ ]
A. the power supply voltage is unchanged, the value of the resistance to change to twice the original
A. power supply voltage is unchanged, the value of the resistance to change to twice the original
A. the power supply voltage, the resistance to change to the original power supply. B. The supply voltage remains unchanged, and the resistance value becomes half of the original
C. The supply voltage and resistance value both become half of the original
D. The supply voltage becomes half of the original, and the resistance value becomes two times of the original
(2006 Laiwu City) The following estimation is in accordance with the facts of family life
A. The electric power of a color TV is about 100% of the power consumption of the original. Color TV power of about 100W B. Writing desk surface area of about 200cm2
C. Bath water temperature of about 70 ℃ D. People stand on the ground with both feet on the ground pressure of about 1000Pa
(2006 Chongqing City, the curriculum reform area) With the gradual improvement of people's living standards, the increasing number of household appliances in the home circuit, the following statements Correct
is ( )
A. Lights and the switch that controls it are connected in parallel, and sockets are connected in series
B. When using a stylus, you can't touch the metal at the end of the pen with your hand
C. One of the reasons why the current in the circuit is too high is that the total power of the electrical appliances used is too high
D. To increase the number of high-powered electrical appliances, you just need to change the fuse to be thick enough
D. The fuse can be changed to a fuse that is thick enough for the electrical appliances you want to use. fuse can be
(2006 Lishui City class reform area) the family circuit fuse blew, the reason may be
A. short circuit B. someone electrocuted C. bulb filament broken D. zero line breaks
(2006 Nantong City class reform area) the following phenomenon in line with the safety of electricity
appliances fire first cut off power supply wet clothes drying on the wire with a wet cloth to wipe electrical appliances household appliances are not grounded
A B C D
(2006 Tai'an City, non-curricular reform area) as shown in the figure of the four circuits, the power supply voltage is the same, , the circuit of the total power consumed by the order from the smallest to the largest
A. a, b, c, d. b, d, b, b, a
C. d. a, b, d, b, b, b
C. d, A, B, C D. C, B, A, D
(2006 Hangzhou) A class of students installed four electric lights after learning about home circuits, which you think are correct
A B C D
(2006 Yancheng City) Regarding the general knowledge of electricity, the following statements are correct (A )
A. The fuse in the fuselage is broken. Replacement can not be replaced with a copper wire
B. Installation of the gate switch, the power inlet can be connected to the upper two terminals, can also be connected to the lower two terminals
C. C. wire connection socket, the firewire can be connected to the left socket, can also be connected to the right socket
D. Screw head when connected to the lamp, the firewire can be connected to the lamp head inside the metal, can also be connected to the screw sleeve
D. Screw set on
(2006 Huanggang) the following meet the requirements of safe use of electricity
(2006 Nanjing) life, the following measures are not in line with the safe use of electricity ( )
A. The metal shell of household appliances should be grounded
B. The switch must be connected to the fire line
C. found that the household electrical appliances or conductor fire, must first cut off the power supply, and then save the fire. C．When you find a fire in a household appliance or a wire, you must cut off the power supply before putting out the fire
D．When you find someone is electrocuted, you should immediately pull the electrocuted person away with your hand
(Quzhou, 2006)
(Quzhou, 2006). Due to the lack of scientific knowledge and casualties caused by accidents occur from time to time, the following practices are correct
A. There is a metal casing of household appliances, the casing of the ground wire can be connected to the zero line of the power supply
B. Do not touch the low-voltage electrically charged body, do not get close to the high-voltage electrically charged body
C. Dilute concentrated sulfuric acid, the water is poured directly into concentrated sulfuric acid
D. Electrical equipment, the first to use water to extinguish a fire, the first to use water to extinguish a fire, the first to use water to extinguish a fire, the first to use water to extinguish a fire. In case of fire, first use water to extinguish the fire, and then cut off the power supply
(2006, Nanjing) In the circuit shown in Figure 8, the supply voltage is constant, Rl is a fixed-value resistor, and Rl is a sliding varistor. power becomes larger
D. Voltmeter V2 becomes smaller, the total power consumed by the circuit becomes
(2006, Tai'an City, non-curriculum reform area) as shown in the figure, when the switch S is closed, found that the lamp L does not light, with a stylus to test the two points c, d, neon tubes are glowing, test a, b two points, only point a neon tube glows, the fault may be
A. the fire wire and the zero line short circuit B. a, a, a, a, a, a, a and a short circuit B. the fire wire and the zero line short circuit B. a, a, a, a short circuit A, a short circuit B. a, a, a, a, a short circuit A. B. a, d somewhere between the circuit break C. b, c somewhere between the circuit break D. lamp filament broken
(2006 Ningbo City) Xiaoming lamp plug into the socket, when he closed the lamp switch. All the other lights in the room went out. The fuse was found to be blown. The cause of this failure may be ( )
A. lamp base short circuit B. socket short circuit C. plug short circuit D. switch short circuit
(2006 Zhejiang Province) in the "measurement of small light bulb power experiment", a class of four students connected to the circuit shown in the figure, which is connected correctly
(2006 Wuxi City) sliding rheostat is a more common electrical equipment. Physics laboratory has a labeled "1012 1A" of the sliding varistor, Xiaoming students studied it, and got some of the following conclusions, which is wrong ( )
A. This sliding varistor can be connected to the circuit of the maximum resistance is 1012
B. When the current in the sliding varistor is not more than 1A, it can be used safely.
C. When the voltage at the ends of this sliding varistor does not exceed 10V, it can be used safely
D. The maximum power consumed by this sliding varistor when it is used safely is 10w
(Fuzhou City, 2006) The scenario shown in Fig. 4 meets the safe use of electricity operation
(Suqian City, 2006) When Xiaoming was doing his homework. found that the light flickered, the reason may be
A. the actual voltage of the bulb changed B. the bulb's rated power changed
C. the bulb's rated voltage changed D. the bulb burned out
(2006 Linyi) the use of electricity to people's production, life has brought a lot of convenience, but if the improper use of electricity will also bring people Hazards, the following practices may bring harm to people are
A. Replacement of light bulbs or repair circuits should be disconnected from the power supply
B. Switch to be connected to the fire wire
C. Three-hole socket grounding wire to ensure a good grounding
D. Temporarily there is no suitable fuse. A short time can be replaced by a thin steel wire
(2006 Taizhou City) Xiaohua ready to participate in the toy car race, he used the circuit shown in Figure 5 to select a motor with high energy conversion efficiency. The voltage of the battery is constant, he first pinched the shaft of the motor so that it does not rotate, closed the switch and read the ammeter reading 2A; then let go of the motor when the motor is rotating normally, and read the ammeter reading 0.6A. The efficiency of the conversion of electrical energy into mechanical energy in the normal rotation of the toy motor is
A. 91% B. 70% C. 30% D. 9%
(2006 Taizhou City, China) p>
(2006 Taizhou City) power meter is to measure the consumption of electrical energy meter, Xiaohua want to verify his home power meter dial labeled per kilowatt hour of the number of revolutions is accurate, so the labeled "220V 3A" of the electrical appliances alone into the circuit, when the electrical appliances work 5min, the power meter's Turntable exactly 110r, the actual number of revolutions per kilowatt-hour meter should be
A. 2400r B. 2000r C. 1500r D. 1200r
(2006 Zhenjiang City) 16, Xiaoming home lighting incandescent bulb filament burned out, his father will be broken filament lapped together and then continue to use the bulb is found to be brighter than usual. The reason is that the filament ( )
A. resistance becomes smaller, the current becomes larger B. resistance becomes smaller, the current becomes smaller
C. resistance becomes larger, the current becomes larger D. resistance becomes larger, the current becomes smaller
(Zhenjiang City, 2006) 18. light Ll labeled with the words "8V 16W", light L2, "12V 36W", "12V 16W", "12V 36W", "12V 36W", "12V 36W", "12V 36W", "12V 36W", "12V 36W", "12V 36W". Marked with the words "12V 36W". Two lights connected in series in the voltage U circuit, to ensure that the two lights are not damaged, the maximum value of voltage U should be ()
A. 8V B. 12V C. 16V D. 20V
(2006 Zhenjiang City) 20. Xiaoming night to do homework, the desk lamp plug in the desk side of the socket, close the desk lamp switch, and found that the desk lamp does not light up. In order to find out the cause of the problem, Xiaoming desk lamp plug into other sockets, found that the lamp can be normal light, with a stylus inserted into the desk side of the socket holes for inspection, found that one of the holes can make the stylus neon tube light. The cause of the failure may be ( )
A. into the household line on the fire wire fuse burned out B. into the household line zero line broken
C. desk side of the socket and the zero line disconnect D. desk side of the socket and the fire line disconnect
(2006 Leshan) 25. a household color television set in normal operation of the electrical power is closest to the B
A ． 1000W B． 200W C. 10W D. 1W
(2006, Shaanxi Province) 6. The following statements about an electric rice cooker are correct (C)
A. The metal surgery can be left ungrounded while it is working. B. It converts internal energy into electricity while it is working.
C. It heats up the food by using heat generated by an electric current. D. It works in series with other home appliances
(Wuhan, 2006) 9. In response to the central government's call to "mobilize the whole nation to build an energy-saving society", Xiaoming puts forward the following suggestions to conserve electricity, of which the unscientific ones are
A. Turn off the lights when you leave the room. B. Replace the electric water heater with a solar water heater
C. Use an electronic high-efficiency water heater to save electricity.
C. use electronic high-efficiency energy-saving lamps D. turn off the air conditioner and open the door of a working refrigerator to lower the room temperature
(Wuhan City, 2006) 12. The following statements about the safe use of electricity are correct
A. As long as a lamp doesn't emit light, you can wipe it clean with a damp cloth
B. As long as a fuse is replaced with a thick one, a high-power electrical appliance can be plugged into the circuit
B. C. You can prevent electric shock by connecting the metal casing of household appliances to the ground wire
D. When you see someone being electrocuted, you should immediately pull him away by hand
(Wuhan, 2006) 13. Xiaoming wants to carry out the following experiments with the circuit diagram shown in the figure. Verify Joule's law
C. Determine the power consumed by resistor R1
D. Verify that the total voltage across the circuit is equal to the sum of the voltages across each part of the circuit
(Shandong Province, 2006) 9. If a TV set, soldering iron, and electric fan are all labeled with the words "220V 60W", they all work at the rated voltage. They are working at rated voltage for the same amount of time, the three appliances produce the most heat
A. TV B. fan C. soldering iron D. as much
(2006 Shandong Province) 12. Mr. Zhang business trip coincided with the day of the meter reading, its electrical energy indicated as shown in Figure 5 (a) shown in the return to the business trip to find that there is a 60W lamp at home is lit, check the other appliances have been cut off the power, and then check the power supply. Electrical appliances have been cut off the power supply, and then check the power meter as shown in Figure 5 (b), the teacher traveled as long as
A. 2400h B. 14.4h C. 0.24h D. 240h
(2006 Beijing) 5. the following kinds of electrical appliances, the use of electric current, the thermal effect of the work of the
A. electric motors B. fans C. cooking pots and pans Refrigerator D. Rice cooker
(2006 Beijing) 8. As shown in Figure 4 of the four practices, in line with the requirements of safe use of electricity
(2006 Beijing) 17. There are four small light bulbs L1, L2, L3, L4, respectively, labeled "12V 20W, "12V 10W", "6V 5W", "6V 10W" of the word, Xiaoming would like to two of the small bulbs connected to both ends of the voltage of 18V power supply, so that the two small light bulbs can be normal light, then the following practices are correct
A. L1 and L4 in series after access to the circuit B. L2 and L4 in series after access to the circuit
C. L1 and L3 in series after access to the circuit D. L2 and L3 in series after access to the circuit
(2006, Hebei Province) 10. shown in Figure 4, the power supply voltage U = 18V, the small light bulb L = 18V, the light bulb L, the light bulb L, the light bulb L = 18V, the light bulb L = 18V, the light bulb L = 18V, the power supply voltage U = 18V, the light bulb L = 18V. Figure 4 shows that the power supply voltage U = 18 V, the rated voltage of the small bulb L is 9 V. When the slide P of the sliding varistor is moved to the midpoint, the small bulb L glows normally; when the slide P is moved to the rightmost end of the actual power of the small bulb L is 6 W. Then the rated power of the small bulb and the maximum resistance of the sliding varistor are
A. 13.5 W 6 Ω B. 6 W 13.5 Ω C. 6 W 12 Ω D. 13.5 W 12 Ω
(2006 Hebei Province) 22. as shown in Figure 7, the power supply voltage U = 18V, the rated voltage of the small bulb L is 9V. when the slide P of the sliding varistor is moved to the midpoint of the small bulb L, the normal light; when the slide is moved to the right end of the small bulb, the actual power of the small bulb 6W. then the small bulb's rated power and the sliding varistor's maximum resistance are
A. 13. 5W 6Ω A.13.5W 6Ω B.6W 12Ω C.6W 27Ω D.13.5W 12Ω
(2006 Dalian) 14.The following household appliances have a rated power close to 800W [ ]
A.lamp B.TV set C.fan D.rice cooker
(2006 Dalian) 18.Refrigerators, washing machines, electric heaters and other household appliances use three-pronged plugs, the purpose of which is to [ ]
A. save electricity B. make electricity available to household appliances
C. prolong the service life of household appliances D. prevent electrocution accidents when the shells of household appliances are electrically charged
(2006 Huaian City) 5. household appliances that work by using the thermal effect of electric current are
A. Rice cooker B. Washing machine C. Refrigerator D. Television set
(2006 Huaian City) 10. The role of fuses in household circuits is to
A. Prevent electric shock B. Stabilize the voltage C. Measure the electrical energy D. Protect the circuit
(2006 Yichang City) 14. After a hotplate is energized, the wire is hot and red while the wire connected to the wire is not so hot. The reason for this is that
A. the current through the wire is large B. the current through the wire is large
C. the resistance of the wire is small, and the heating power is small D. the resistance of the wire is small, and the heating power is small
(2006 Huanggang) 5. In the household use of electricity, the requirements for the use of electricity are met
(2006 Shenzhen) 9. the following common sense about household electricity use is correct
(2006 Shenzhen) 9. Common sense is correct
A, the metal casing of household appliances do not need to ground wire
B, standing on a dry wooden bench at the same time touching two wires will not be electrocuted
C, found that someone electrocuted, the power supply should be cut off as soon as possible
D, wet hands can be directly switched on and off the electrical appliances
Three, diagramming, experiments, and scientific investigations
(2006, Laiwu City) (Laiwu City, 2006) to determine the power rating of the small light bulb experimental equipment shown in Figure 8, which is labeled with a small light bulb "3.8V" of the word, its resistance is about 10Ω.
(1) Please use a pencil line instead of wire, the equipment in Figure 8 connected to the experimental circuit (wires do not cross).
(2) Xiaogang reasonably well connected to the circuit, close the switch, no matter how to adjust the sliding varistor bulb does not light. So Xiaogang put forward the following conjectures:
A. may be broken filament
B. may be a short-circuit bulb
C. may be an open circuit varistor
Which conjecture is correct, can be based on the ammeter and voltmeter to determine the number of (ammeter, voltmeter are not faulty). The table below gives several possible situations for the ammeter and voltmeter, determine which conjecture is correct in each case and put its serial number in the corresponding space.
Ammeter Voltmeter Judgment Results
Display is not zero Display is zero
Display is zero Display is not zero
Display is zero Display is zero
(3) Xiaogang troubleshooting, adjusting the sliding rheostat to make the small bulb light up normally, at this time the current is indicated as shown in Fig. 9, then the current through the small bulb is ________________A, and the rated power of the bulb is ________________W.
Ammeter Voltmeter Judgment Results
Display is not zero Display is zero B
Display is zero Display is not zero A
Display is zero Display is zero C
Answers: (1) Slightly (2) < /p>
(3) 0.36, 1.368
(2006 Nantong City, class reform area) in the "measurement of small light bulb electric power" experiment, known as the power supply for the two lead storage batteries, the small bulb's rated voltage of 2.5V, resistance of about 10W, the sliding rheostat labeled with "20W lA'' words, a student has been connected to part of the circuit as shown in Figure A.
(1) the students connected to the circuit has a mistake, please use a pen to cross "×" marked in the error.
(2) After the error is corrected, please use a pencil line instead of wire, in Figure A to connect the circuit is complete.
(3) close the switch, move the slide of the varistor to a position, the voltage is 2.5V, the current is shown in Figure B, then the current in the small bulb is ______A, the small bulb's rated power is ____________W.
(4) another student connected to the circuit and closed the switch, found that the small bulb is first very bright after the light goes out, do you think he may have a problem when connecting the circuit. think the problem he may have in connecting the circuit is ______________________________________________________.
(2006 Jiangxi Province) before the midterm exams, his father in order to have a comfortable learning and living environment at home, bought a new air conditioning, installed, just after the use of all electrical appliances in the home have stopped working, after checking the fuse has blown. (l) Try to analyze the cause of the blown fuse. (2) to make the person connected to the air conditioning, all appliances at home can work properly, the family circuit should be how to improve?
(2006 Yancheng City) the use of the experimental equipment shown in the figure, to determine the rated voltage of 6V small light bulb electric power. It is known that the sliding varistor labeled "12Ω 1A", the supply voltage remains unchanged.
Experimental steps are as follows:
A. Connect the circuit. Draw a wire on the A diagram, making the determination of the electric power of the small light bulb circuit is complete, the requirements of the slide P to the right, the small light bulb dimmed.
B. After connecting the circuit, to make the resistance of the sliding varistor all the way into the circuit, you should move the slide P to the end, and then close the switch S. At this time, the voltage is 4.2V, and the corresponding current is shown in Figure B.
C. Adjust the slide, when P is moved to the middle point of ab, the small light bulb just normal light.
D. Continue to adjust the slide, when P moved to another point, the light bulb is bright, read the voltmeter, ammeter value of 6.5V, 0.52A, recorded in the table below.
Number of experiments Voltmeter/V Current/A Brightness Power/W
1 4.2 Dim
2 6.0 Normal
3 6.5 0.52 Brightness 3.38
Please fill in all the data in the blanks of the table above, and then analyze the information in the table. The conclusions obtained are (writing two is enough): ?
;
.
(2006 Jiangxi Province) in the determination of "small light bulb electric power" in the experiment, known as the power supply voltage of 6V, the rated voltage of the small bulb is 2.5V, the resistance of the small bulb is about 10