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As shown in figure a is the circuit diagram of "measuring the rated power of small bulb", the power supply is two dry batteries; the small bulb is marked with the word "2.5V", the resistance is about 10 ohm, and it is slippery
Because the resistance of the filament increases with the temperature, it does not meet the control variable conditions
The equation of a straight line passing through point a (0,3) and having only one common point with hyperbola x ^ 2 / 4-y ^ 2 / 9 = 1
Follow the site oblique, set to
y=kx+3
Substitute into hyperbolic equation
We get a function of degree 2
If there is only one intersection, then b-4ac = 0
The solution is k = the root of plus or minus 2 / 6
So the equation is y = 2 / root 6x + 3 or y = negative 2 / root 6x + 3
… If I'm right, I'll give it to you~
Copper wire of the same length has different thickness, which has higher resistance
The resistance is directly proportional to the length and inversely proportional to the cross-sectional area
Given that F1 is an ellipse X & # 178;; / 25 + Y & # 178;; / 9 = 1 in the left focus, P is the moving point on the ellipse, and a (1,1) is a certain point, what is the maximum value of PA + Pf1
First, through checking calculation, we know that a (1,1) is inside the ellipse; if the major axis 2a of the ellipse is 10, and the right focus coordinate F2 (4,0), then af2 = √ [(1-4) ^ 2 + (1-0) ^ 2] = √ 10; so the maximum pa + Pf1 = 2A + af2 = 10 + √ 10; as shown in the figure above, the sum of the distances from any point of the ellipse to a and F1 is P & # 39; a + P & # 39; F1 & lt; (P & # 39; F2 +
How many watts is one degree of electricity? Can we change the wattage of our light into degree? Take 25 watts as an example
1 degree of electricity = 1 kWh
The wattage of the light we use multiplied by time can be changed into degrees
Take 25 watts as an example, it costs 1 kilowatt hour to turn on the light continuously for 40 hours
25 * 40 = 1000 watt hours
1. Given that the moving point P (x, y) satisfies | X-1 | + | Y-A | = 1, O is the origin of the coordinate, if the value range of the maximum value of | Po | is [root 13, root 17], then the value range of the real number a is____ .
The answer is [- 3, - 1 / 2] and [1 / 2,3]
2. Given the ellipse x * 2 / 16 + y ^ 2 / 4 = 1, the left and right focal points are F1 and F2 respectively, and the point P is on the straight line L: X - (radical 3) * y + 8 + 2 * (radical 2) = 0. When ∠ f1pf2 takes the maximum value, then the value of | Pf1 | / | PF2 | is____ .
Root three minus one
1. It's easy to see which is the farthest point and which is the nearest point
2. I don't know which is rooted in the second question
The rated voltage is 220 V, and the rated power is 100 W and 250 W respectively. The lamp is connected to the power supply in series. Which lamp is on? Parallel connection? Detailed process ≡ [.] ≡
Series known: 100W bulb resistance is large, 250W bulb resistance is small, so when in series, the current is the same, according to the series voltage, 100W bulb voltage is high and P = UI, so the actual power P 100W bulb power is greater than 250W bulb power, so 100W bright parallel shunt voltage constant is the rated voltage
How to use 23.5 * 4 + 4.77/0.25 for simple calculation
This question is divided by 0.25, not multiplied
0.25 = 1 / 4, so 23.5 * 4 + 4.77 / 0.25 = (23.5 + 4.77) * 4
Why is the resistance calculated by Ohm's law when the motor is working larger than that calculated by Ohm's law when it is not working?
I know that Ohm's law cannot be used in non pure resistance circuits
The power of electricity has also increased
When the motor is working, the electric energy is mainly converted into mechanical energy, which is a non pure resistance circuit. Ohm's law can not be used to calculate the pure resistance, but the impedance value of the coil is large; when the motor is not working (stop rotating), the power consumption is small, and the electric energy is converted into internal energy, which is calculated to calculate the resistance value is small
0.24 * 15 / (3.25-2.35) recursive equation calculation
Sorry! I'll ask you another question!
=0.24×15÷0.9
=3.6÷0.9
=4
RELATED INFORMATIONS
- 1. Does dry battery convert electric energy into chemical energy or chemical energy into electric energy? The answer is that chemical energy is converted into electrical energy. Why? I can't figure it out! I always think that electrical energy is converted into chemical energy
- 2. A resistance R to be measured and current a are connected in series in the circuit shown in the figure. At this time, the indication of the ammeter is I1. If a constant resistance R0 with known resistance value is connected in series in this circuit, the indication of the ammeter becomes I2. According to the above data, the resistance value of the resistance Rx to be measured can be obtained——
- 3. As shown in the figure, if the line segments a and B are known and a > 3 / 2B, use a compass and a ruler to find a line segment X so that x = 2a-3b fast
- 4. It can be made up of four different numbers: 1, 2, 3 and 4______ Four digits without repetition
- 5. If the speed of the bicycle is always a, the speed of the car is always B. If b = a + 1, who will arrive first? Party A and Party B start from a to B at the same time. The way to take this part of the road is to ride a bicycle for the first two-thirds of the distance and take a car for the last one-third of the distance. Party B's way is to ride a bicycle for the first two-thirds of the time and take a car for the last one-third of the time. If the speed of the bicycle is always a and the speed of the car is always b, if B = a + 1, who will arrive first?
- 6. On a 1:6000000 map, the distance between Beijing and Shanghai is 17.5cm How many hours does it take for a car to go from Beijing to Shanghai at the speed of 84 kilometers per hour?
- 7. The distance between the two places is 270 kilometers. A and B cars leave from the two places at the same time. They meet in three hours. The speed ratio of a and B cars is 5:4, and the speed of the two cars is 5:4 The distance between the two places is 270 kilometers. A and B cars leave from the two places at the same time and meet each other in three hours. The speed ratio of a and B cars is 5:4. What's the speed of the two cars?
- 8. The number of male workers accounts for 60% of the total number, and the number of female workers is equal to ()
- 9. 5 / 8 of a is equal to 5 / 9 of B. A: B = (): ()
- 10. What is the relationship between indefinite integral and original function?
- 11. It is difficult to connect the 220V 100W and 220V 40W A and B in series to the 440V power supply a. They all glow normally b. The nail may burn out c. It may be burnt out d. The current works as much on the light
- 12. Let n-dimensional vector group A1, A2,..., as, as + 1 (s)
- 13. If E1 and E2 are a group of bases in the plane, then the following four groups of vectors can be used as bases of plane vectors A、e1-e2,e2-e1B、2e1-e2,e1-1/2e2C、2e2-3e1,6e1-4e2D、e1+e2,e1-e2
- 14. The equations X / 2-y + 1 / 3 = 1,3x + 2Y = 10
- 15. As shown in the figure, in the parallelogram ABCD, the diagonal lines AC and BD intersect at point O, and the straight lines passing through point O intersect AD and BC at points m and N respectively. If the area of △ con is 2 and the area of △ DOM is 4, then the area of △ AOB is 2______ ．
- 16. Known circle C: (x-1) ^ 2 + (Y-2) ^ 2, through the point P (2, - 1) as the tangent of circle C, the tangent points are a and B Known circle C: (x-1) ^ 2 + (Y-2) ^ 2 = 2, through the point P (2, - 1) as the tangent of circle C, the tangent points are a and B
- 17. The function f (x) = 1 / 2x ^ 2-alnx is known. When a = - 1, it is proved that the function f (x) increases monotonically on (0, + infinity). 2 find the extremum of F (x)
- 18. Is f (x) = - x + 2x + 1 x an increasing or decreasing function on [1, positive infinity]
- 19. Given the function f (x) = 2x / x2 + 1, we prove that it is a decreasing function in [1, positive infinity]
- 20. It is proved that f (x) = X-1 / X is an increasing function in the interval (0, positive infinity) It's x minus 1 / X. it's a detailed process. Thank you~~~