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As shown in the figure, the voltage at both ends of the power supply does not change, and the resistance value of resistance R1 is 2 Ω. Close the switch S. when the slide P of sliding rheostat is at point a, the indication value of voltmeter V1 is 4V, and that of voltmeter V2 is 10V. When the slide P of sliding rheostat is at point B, the indication value of voltmeter V1 is 8V, and that of voltmeter V2 is 11V. Then the resistance value of resistance R2 is 4V___ Ω．
According to the constant total voltage, the sum of the indication of voltmeter V2 and the voltage at both ends of R1 should be the power supply voltage. The sum of the indication of voltmeter V1 and the voltage at both ends of resistance R2 is also the power supply voltage. According to the equal power supply voltage, the following equation can be obtained: 10V + i1r1 = 11V + i2r1 ①4V+I1R2=8V+I2R2… ② It can be reduced to R1 (i1-i2) = 1V ③R2（I1-I2）=4V… ④ Substituting R1 = 2 Ω into ③ and ④, the solution is R2 = 8 Ω, so the answer is 8 Ω
As shown in Figure 9, the voltage at both ends of the power supply does not change, and the resistance value of the resistor R1 is 2 Ω. Close the switch s, when sliding the slide P of the rheostat
When p is at the middle point, the current is I1 and the resistance is 0.5r2. When p is at the maximum resistance, the current is I2 and the resistance is r2i22r1 = q / T = 60j / 15s = 4wi1 × 0.5r2 = 4vi2r2 = 6V
As shown in the figure, the voltage at both ends of the power supply does not change, and the resistance value of resistance R1 is 2 Ω. Close the switch S. when the slide P of sliding rheostat is at point a, the indication value of voltmeter V1 is 4V, and that of voltmeter V2 is 10V. When the slide P of sliding rheostat is at point B, the indication value of voltmeter V1 is 8V, and that of voltmeter V2 is 11V. Then the resistance value of resistance R2 is 4V___ Ω．
According to the constant total voltage, the sum of the indication of voltmeter V2 and the voltage at both ends of R1 should be the power supply voltage. The sum of the indication of voltmeter V1 and the voltage at both ends of resistance R2 is also the power supply voltage. According to the equal power supply voltage, the following equation can be obtained: 10V + i1r1 = 11V + i2r1 ①4V+I1R2=8V+I2R2… ② To turn into
In the circuit as shown in the figure, the power supply voltage remains unchanged, the setting resistance R1 = 10 Ω, R2 is the sliding rheostat,
The indication of ammeter is 0.3A; when slide P is at B end, the indication of voltmeter is 2V
Switch
│ │
│ ┌———V ————┐
A │ │
│ │ ┌—┘
│ │ ↓P
└——□———┘——————□
R1 a R2 b
This girl, endless. Fortunately I can understand your picture. =. =!
A meter is still used to measure the main circuit current. V meter is used to measure the voltage at both ends of R2. R1 and R2 are connected in series
When p is at a end, the resistance of R2 access circuit is 0, the reading of a meter is the current on R1, u = 0.3x10 = 3V = power supply voltage
When p is located at the B end, the whole resistance of R2 is connected to the circuit. In this case, the reading of V meter is the voltage at both ends of R2. According to the series voltage division, the voltage at both ends of R1 = 3-2 = 1V
At this time, the current on R1 = the current on R2 = 1V / 10 Ω = 0.1A
R2 = voltage / current at both ends = 2V / 0.1A = 20 Ω
P2=U2·I2=2V X 0.1A=0.2W
RELATED INFORMATIONS
- 1. In the circuit shown in the figure, close the switch s and move the slide P of the sliding rheostat. When the indication of the voltmeter is 6V, the indication of the current is 0.5A; when the indication of the voltmeter is 7.2V, the indication of the ammeter is 0.3A. Then the resistance R0 is 0______ Ω, the power supply voltage is______ V．
- 2. As shown in the figure, the voltage at both ends of the power supply remains unchanged, and the resistance value of resistance R1 is 2 Ω. Close switch S. when slide P of sliding rheostat is located at point a, the indication value of voltmeter V1 is 4V, and that of voltmeter V2 is 10V. When slide p of sliding rheostat is located at point B, the indication value of voltmeter V1 is 8V, and that of voltmeter V2 is 11V______ W．
- 3. There is a DC power supply whose internal resistance can be neglected to deliver current to the series resistor A. B. when the 90 ohm resistor a is short circuited, the current in the circuit is four times that before the short circuited, then the resistance value of the resistor B is?
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- 6. What determines the resistance? What determines the size of the resistance?
- 7. The resistance of a conductor is related to which three factors of the conductor. For the same material, the longer the conductor is and the smaller the cross-sectional area is, the greater the resistance of the conductor is?
- 8. Will the parallel diode or resistance of the relay coil affect the overall resistance?
- 9. Under what circumstances are relay coils connected in parallel with resistors and capacitors
- 10. The resistance of metal conductor increases with the increase of temperature? Why? Is it necessary to add something in front?
- 11. When a student was doing the experiment of measuring the resistance of a small light bulb, he connected the circuit, closed the switch and found that the light bulb did not emit light (1) When doing the experiment of measuring the resistance of a small bulb, a student connected the circuit, closed the switch, and found that the bulb did not emit light, the ammeter showed the number, and the voltmeter did not show the number. After inspection, it was found that there was only a fault at the bulb, so the reason for the above phenomenon may be () (2) When doing the experiment of measuring the resistance of a small bulb, a student connected the circuit and closed the switch. He found that the bulb was not on, the ammeter did not show the number, and the voltmeter had a large number. The reason for the above phenomenon may be () Urgent, must tell me why, by the way, short circuit, open circuit and other differences
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- 13. A uniform thickness metal wire is stretched to twice the original length and cut into two sections, one of which is resistance A wire of uniform thickness is drawn twice as long as the original wire and cut into two sections from the middle, one of which has a resistance of -
- 14. The resistance of a uniform wire will be cut into two equal sections and the two sections will be twisted together
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- 20. Conductivity unit: 1ms / cm = () us / cm