The current of a 5 Ω resistor passing through it is 2a, and the heat released in 10 seconds is 2______ J. If the current through it is reduced to the original 12, the heat released in the same time is the original______ &Set the resistance value unchanged

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• 1. Fill in "ten, one, X. /" or () on the left side of the following formulas to make the equation hold Fill in "ten, one, X. /" or () on the left side of the following formulas to make the equation hold 9 9 9 9 9 =17 9 9 9 9 9 =18 9 9 9 9 9 =19 9 9 9 9 9 =20
• 2. Resistance R1 = 1 ohm, R2 = 1000 ohm, if they are connected in parallel in the circuit, then the total resistance is A. More than 1 euro B. Less than 1 ohm C. More than 1000 Ω D. Greater than 1 ohm and less than 1000 ohm
• 3. What is the sequence of question marks 2,6,2,7,13,12,8,10,4,18,2,6,11,12,9,22,13
• 4. Explore the relationship between current, voltage and resistance Keep the constant resistance R = 10 Ω, close the switch s, adjust the sliding rheostat r so that the voltage at both ends of the constant resistance R is 1V, 2V and 3V respectively. Read out the ammeter and record in the table, analyze the data and draw a conclusion Step 2: let the constant resistance be 5 Ω, 10 Ω and 15 Ω respectively, keep the voltage at both ends of the constant resistance u = 2V unchanged, read out the ammeter indication and record it in the table, analyze the data and draw a conclusion Please design the form required in step 2 based on the above materials In step 2, what is the operation method to keep both ends of the constant resistance unchanged? The ammeter used by Xiao Ming has two ranges: 0-0.6a and 0-3A. According to your existing knowledge and experience, which range do you think he should use and why?
• 5. (1*3*5+2*6*10+3*9*15+4*12*20)/(1*2*3+2*4*6+3*6*9+4*8*12) jiansuan
• 6. When the slide of sliding rheostat moves, the indication of ammeter and voltmeter in the circuit changes
• 7. The quadratic equation (x-3) ² = 5 is reduced to the general form of (x-3) ² = 5
• 8. Motor, u = 110V, r = 0.4 ohm, normal operation, I = 0.5A, find 1. Work done by current per second, heat generated per second, Q
• 9. The surface area of the cuboid is () square decimeter and the volume is () cubic decimeter
• 10. The surface area of this cuboid is () square decimeter, and its volume is () cubic decimeter
• 11. When we know the value of the first-order function y = (6 + 3M) x + (M-4) m, the function image intersects the Y axis on the negative half axis
• 12. How to calculate the 380V voltage divided into several 220V currents in the distribution box There is a distribution box on the second floor. The main power supply is led from the switch cabinet on the first floor. The air switch in the distribution box on the second floor is like this. The total air switch is ABC three-phase power, and N and PE are directly connected to the line, There are five 1p air switches in the distribution box for lighting, and the power is like this: the first air switch is 3500W, the second is 5000W, the third is 2500W, the fourth is 1000W, and the fifth is 2000W There are four two p air switches with leakage protection in the distribution box, which are used for sockets. The power is like this: the first is 2000W, the second is 1500, the third is 2600, and the fourth is 2400W There are also six 380V 3P air switches in the distribution box, two for air conditioning, both of which are 7 kW, What is the current of this distribution box, (please tell me the calculation method) how thick cable should I choose 2. Should I choose 3P air switch or moulded case circuit breaker for the general air switch of the distribution box on the second floor 3. Is the cable leading from the second floor to the first floor switchgear directly pressed on the copper bar in the switchgear, or is the cable led from the copper bar through the molded case circuit breaker and then pressed on the molded case circuit breaker? If it passes through the molded case circuit breaker, what size of the circuit breaker should I choose 4. What size of the total air switch in the distribution box on the second floor should I choose, the same as the rated current or twice the rated current
• 13. The perimeter of a circular fountain is 37.68 meters. How many square meters does the circular fountain cover?
• 14. A circular fountain with a diameter of 8 meters is paved with a 1 meter wide path around it. How many square meters is the area of this path?
• 15. There is a circular fountain in the center of the seaside park with a radius of 4 meters. A 2-meter-wide path should be built around the fountain. How many square meters is the area of the path?
• 16. A round fountain is 20 meters in diameter. Now we need to build a 1 meter road around the fountain. How many square meters does the road cover?
• 17. Each circular landscape fountain in the park is 10 meters in diameter. There is a 12 meter wide path around the fountain. Can you calculate the area of the path?
• 18. A cylindrical spray tank, with an inner diameter of 8m, can hold up to 25.12m3 of water. How many meters deep is the tank?
• 19. The school builds a round fountain with a volume of 37.68 cubic meters and a diameter of 4 meters A. 2B. 3C. 0.6D. 5
• 20. The school builds a round fountain with a volume of 37.68 cubic meters and a diameter of 4 meters A. 2B. 3C. 0.6D. 5