As shown in the figure, the power supply voltage remains unchanged. Close switches S1 and S2, the voltage indication is 6V, and the current indication is 0.6A. After S2 is disconnected, the voltage indication becomes 2V, and the resistance and power supply voltage of R2 are () A. 10Ω、9VB. 20Ω、6VC. 20Ω、9VD. 10Ω、6V

Close switch S1 and S2, the voltmeter measures the voltage at both ends of R1, that is, the power supply voltage is 6V; resistance R1 = ui1 = 6v0.6a = 10 Ω, disconnect switch S2, the circuit current I = u1r1 = 2v10 Ω = 0.2A, the voltage at both ends of R2 U2 = u-u1 = 6v-2v = 4V, R2 = u2i = 4v0.2a = 20 Ω, so select B

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1. As shown in the figure, draw three semicircles with the three sides of the right triangle as the diameter. If the areas of the two small semicircles are known to be S1 = 8 and S2 = 18, then S3 =? A.10 B.13 C.26 D.25
2. As shown in the figure, it is known that in △ ABC, ∠ ACB = 90 °, take each side of △ ABC as an edge and make three squares outside △ ABC. S1, S2 and S3 represent the area of the three squares respectively. S1 = 81 and S2 = 225, then S3 = () A. 16B. 306C. 144D. 12
3. As shown in the figure, △ ABC is a right triangle, S1, S2 and S3 are squares, a, B and C are known to be the side lengths of S1, S2 and S3 respectively, then () A. b=a+cB. b2=acC. a2=b2+c2D. a=b+2c
4. As shown in the figure, take the three sides of RT △ ABC as the sides and make three equilateral triangles outwards. Their areas are represented by S1, S2 and S3 respectively. Please guess the quantitative relationship between S1, S2 and S3 and explain the reason
5. In Fig. 1, three semicircles are made outward with three sides of RT △ ABC as diameters, and their areas are expressed by S1, S2 and S3 respectively. It is not difficult to prove that S1 = S2 + S3. (1) (1) As shown in Figure 2, take the three sides of RT △ ABC as the sides and make three squares outward, and their areas are represented by S1, S2 and S3 respectively. Write down their relationship. (it is not necessary to prove) (2) As shown in Figure 3, take the three sides of RT △ ABC as the edges and make regular triangles outward, and their areas are represented by S1, S2 and S3 respectively. Determine their relationship and prove it; (3) If three general triangles are made outward with three sides of RT △ ABC, and their areas are expressed by S1, S2 and S3 respectively, what conditions should be satisfied for the triangle to have the same relationship with (2) between S1, S2 and S3?
6. Take the three sides of RT triangle ABC as the diameter and make three semicircles outwards. What is the quantitative relationship between their areas S1, S2 and S3?
7. Take the three sides of RT △ ABC as the edge, make three general triangles outward, and their areas are expressed by S1, S2, S3 respectively, to determine the relationship between S1, S2, S3
8. A formula for calculating acceleration by successive difference method in physics of grade one of senior high school (with explanation) I know seven points first, then S4-S1 s5-s2 s6-s3 And then what?
9. The displacement of an object is S1 in the first 3 seconds and S2 in the last 3 seconds The displacement of an object in the first 3 seconds is S1, and that in the last 3 seconds is S2. Given s2-s1 = 6m, S1: S2 = 3:7, the total length of the inclined plane can be calculated The slide is accelerating. Let the length of slope be l and the total time be t L=a*t^2 / 2 S1=a *3^2 / 2 S2=L－[ a*( t －3)^2 / 2 ]=3at－4.5a 3/7=(a *3^2 / 2)/(3at－4.5a) T = 5 seconds 6=(3at－4.5a)－(a *3^2 / 2) a=1m/s^2 L = 12.5A = 12.5m
10. It is known that S2 + S1 = 1.2m, S1: S2 = 3:7, and the total length of the inclined plane is 1.2m?
11. In the circuit shown in the figure, the power supply voltage remains unchanged. When the switch S1 is closed, the lamp l will light up. If the switch S2 is closed again, then () A. The number of two ammeters increases B. the brightness of light l decreases C. The total resistance of the circuit decreases D. the number of voltmeters increases
12. In the circuit shown in the figure, the power supply voltage is 3V. When the switches S1 and S2 are closed, then () A. The indication of voltmeter is 3vb. Lamp L1 is not on, lamp L2 is on. C. ammeter will be burned out. D. both bulbs will be burned out
13. In the circuit shown in the figure, the power supply voltage remains unchanged. When the switches S1, S3 are closed and S2 is disconnected, the current representation is 1.8A. When S1 is closed and S2, S3 is disconnected, the current representation is 0.6, A. when S2 is closed and S1, S3 is disconnected, the power consumed by R2 is 1.6W, The range of 2.5 a sliding rheostat ammeter is 0-0.3a. When S1 and S3 are closed and S2 is disconnected, what is the minimum resistance in the sliding rheostat access circuit
14. The area formula of triangle formed by linear function y = KX + B and coordinate axis Come on! Thank you
15. When the line L passes through the point P (2,1) and the area of the triangle enclosed by the positive half axis of the two coordinate axes is the smallest, the equation of the line L is obtained
16. Given that the area of the triangle formed by the line L passing through the point P (- 5,4) and the positive half axis of the two coordinate axes is 5, the equation of the line L is obtained,
17. The area of the triangle formed by the line L passing through a (1.2) and the positive half axis of the two coordinate axes is four, and the linear equation is obtained
18. Given that the area of the triangle bounded by the line L passing through the point P (1,3) and the positive half axis of the two coordinate axes is 8, the equation of the line L is obtained
19. Given the point a (3,2), the line L: x + 2y-3 = 0. Find the minimum area of the triangle bounded by the point a and the positive half axis of the two coordinate axes and the linear equation at this time
20. When the area of the triangle formed by the line L passing through the point P (2,3 / 2) and the positive half axis of two coordinate axes reaches the minimum, the equation of line L is obtained