Let's give you some questions about electric power in the second grade of junior high school

Let's give you some questions about electric power in the second grade of junior high school

Electrical work and power in Physics
1、 Fill in the blanks (1 point for each blank, 20 points in total)
1. The work done by the current in a certain section of the circuit and________ 、________ And________ The instrument for measuring electric power is
________ .
2. The main components of electric heater are________ It uses electricity________ effect.
3. A consumer marked "220 V 44 W" is connected to a 110 V circuit, and the actual power is________ W. (assuming its resistance is constant)
At 4.1 kwh, 25 W light bulb can be used to light normally________ h.
5. When the bulb with 40 W power works normally for 25 hours, the energy consumed is 0________ J. He________ kWh.
6. There is a battery car with working voltage of 24 V, working current of 50 A and efficiency of 80%
When the gravity is 1000 N and the resistance of the battery truck is 0.1 times of the vehicle weight, the vehicle can run at a constant speed of 400 m, and the time required for the battery truck to run at a constant speed is 10 minutes
________ .
7. The number of revolutions per kWh is marked on the dial of a household electric energy meter. For example, the dial of an electric energy meter is marked with "3000 R / kWh", which means that for every 1 kwh of electric energy consumed, the electric energy meter turns 3000 circles. There is an electric furnace, and its electric power is unknown. If the electric energy meter is used to measure the electric power of the electric furnace, what equipment is needed________ The data to be measured are________________ The expression of electric power of electric furnace is________________________ .
8. At the beginning of August, the electricity meter of a family was 3248.6 degrees. It is known that this family has a 75 W color TV set, which uses 4 hours on average every day, three 40 W electric lights, which uses 2 hours on average every day, and one 140 w refrigerator, which uses 10 hours on average every day. So at the end of the month, the electricity meter number is________ Degree
9. There is a "220 V 500 W" electric furnace, which is connected to the 220 V circuit and consumes 0.4 H________ The current through the wire is________ A. The current is measured within 1 s________ Merit
10. Two lamps L1 and L2 in series in the circuit. If the resistance of L1 is greater than that of L2, then________ The voltage at both ends is large, and the current passes through in the same time________ Much work has been done
2、 Multiple choice questions (3 points for each sub question, 42 points in total)
11. Connect a bulb directly to the power supply, the power is 100 W. connect the bulb in series with a long wire to the same power supply, the power is 91 W, then the power loss on the wire is 100 W
A.19 W B.9 W C.10 W D.1 W
12. For a resistance wire, if the current passing through it increases to twice of the original, its electric power increases to twice of the original
A. 2 times b.4 times c.8 times D.1 times
13. A "220 V 60 W" bulb, if connected to 110 V power supply, the actual power of the bulb is
A.30 W B.15 W C.20 W D.40 W
14. In the circuit shown in the figure, when the switch S is closed, the following judgment is correct
A. Both lights go on. B. both lights go dark
C. A lights up, B lights down, D. a lights down, B lights up
15. After connecting the two bulbs marked with "220 V 200 W" and "220 V 40 W" in series and connecting them into the 380 V circuit, what will be burnt out is
A. "40 W" bulb B. "200 W" bulb
C. "40 W" and "200 W" bulbs D. cannot be determined
16. Two resistors are connected in the same circuit, and the voltage at both ends of them is equal. The following judgment is wrong
A. They may be in series or in parallel
B. The current through them must be equal
C. They may have the same resistance
D. The work done by the current must be equal when each resistor passes through 1 C
17. Two fixed value resistors R1 and R2, the resistance values are 10 Ω and 30 Ω respectively, and the maximum allowable current is 1 A and 0.5 A respectively. They are connected in series in the circuit. The following statement is correct
A. The maximum voltage applied to both ends is 25 v
B. Their total resistance is 7.5 Ω
C. The current through the circuit is not allowed to be greater than 1 A
D. Their maximum total power is 10 W
18. The power supply voltage is 6 V, R1 is the sliding rheostat, and its adjustment range is 0 ~ 20 Ω, R2 is a constant resistance with resistance value equal to 20 Ω, and the electric power consumed by the sliding contact P and R2 of the sliding rheostat is adjusted
A. The maximum is 1.8 w B. the maximum is 0.9 w C. The minimum is 0.9 w D. the minimum is 1.8 W
19. In a circuit with constant power supply voltage, a temperature adjustable electric heater is connected. There are two electric heating wires with unequal resistance inside the electric heater. When two electric heating wires are used in series, the electric power consumed by the electric heater is 220 W. when only one electric heating wire with larger resistance is used, the electric power consumed by the electric heater is 275 W. if two electric heating wires are used in parallel, the electric power consumed by the electric heater is 220 W, The electric power consumed by the electric heater is
A.495 W B.990 W C.1100 W D.1375 W
20. There is an electric furnace marked with "220 V or 110 V, 500 W", its corresponding wire connection is shown in the figure, and its B is the intermediate contact of the heating wire AC
A. Connect a and B terminals with 220 V power supply, and the power is 500 W
B. Connect a and C terminals with 220 V power supply, and the power is 500 W
C. Connect a and C together as a terminal, and then connect them and B with 110 V power supply with 500 W power
D. Connect the A and C terminals with 110 V power supply, and the power is 250 W
21. Xiaogang uses an electric energy meter to measure the electric power of a household appliance. When only one appliance in the circuit works, the measured energy consumption is 0.3 kwh within 15 minutes, which may be
A. Air conditioner B. refrigerator C. television D. incandescent lamp
22. The energy meter is connected to the home circuit for measuring
A. Current B. voltage C. electric power D. electric power
23. There are two electric furnaces (furnace a and furnace b). The resistance of furnace a is known to be greater than that of furnace B. the resistance of furnace a is known to be greater than that of furnace B. the resistance of furnace a and furnace B are respectively connected to the circuit with power supply voltage of 220 v. in the same period of time, their heat release conditions are as follows
A. A more exothermic B. B more exothermic C C. as much D. not sure
24. In order to double the heat generated by the electric heater in unit time, the following are feasible
A. Parallel a same resistor
B. Connect the same resistor in series
C. Double the voltage across the resistor
D. Cut the resistance wire into two sections from the middle, and then use them in parallel
3、 Experimental questions (7 points for each sub question, 14 points in total)
25. In order to determine the rated power of a small bulb with a rated voltage of 2.5 V, the equipment as shown in the figure is provided
(1) The principle is________________________ .
(2) The equipment provided in the experiment are: small light bulb, power supply, wire, switch, sliding resistor with large resistance________ And________ .
(3) Draw the experimental circuit diagram in the space below
(4) Use stroke lines instead of wires to connect the equipment in the physical diagram according to the circuit diagram
26. In the experiment of "measuring the power of small bulb", the small bulb to be tested is marked with "3.8 V"
(1) At least use it________ Two dry batteries are connected in series
(2) If it is found that the reading of the voltmeter is 2.5 V after closing the key, the sliding rheostat should be adjusted so that the resistance of the sliding rheostat connected to the circuit changes________ (choose "big" or "small")
(3) After closing the key, adjust the sliding rheostat. The three groups of data measured are as follows. The ampere representation of the third group of data is shown in the figure. Please read out the data and record it in the table below. Please calculate the rated power of the small bulb P =________ ．
Test times voltage indication (V) current indication (a)
1 3 0.19
2 3.8 0.25
3 4.2
(4) If the voltmeter and ammeter are interchanged in the process of experiment, the phenomenon of small light bulb is wrong________ (fill in "not bright", "very bright", "normal light" or "burned")
4、 Calculation questions (8 points for each sub question, 24 points in total)
27. In the circuit as shown in the figure, the small bulb L is marked with "8 V 3.2 W", the maximum resistance of sliding rheostat is 40 Ω, and the resistance of R1 is 18 Ω
(1) The resistance of small bulb L
(2) When s, S1 and S2 are closed, the indication of voltmeter is 9 v. calculate the power consumed on power supply voltage and resistance R1
28. According to the learned electrical knowledge, the distance between two places can be measured by voltmeter. As shown in the figure, a "220 V 100 W" light bulb is connected to a construction site at Part B. the voltage between two poles of power supply at part a is 220 V, the voltage between two ends of light bulb at part B is 193.6 V, and the resistance of aluminum conductor for transmission is 0.02 Ω per 1 m long, From this we can know the distance m between a and B
When the resistance of the oven is 2 × 104 per minute, the resistance of the oven can be calculated
[reference answer]
1. Voltage resistance current energy meter
2. Resistance heating
three point one one
4. 40
5.3.6×106 1
6.42 s
7. Stopwatch T, N P = 3.6 × 106 n / 3000 t
8.3335.6
9.0.2 2.3 500 J
10.L1 L1
11.B 12.B 13.B 14.D 15.A 16.B 17.D 18.A 19.D 20.B 21.A 22.C 23.B 24.A
25 ~ 26
27.20 Ω 9 V 4.5 W
28.1650 m
29.125 Ω 500 W