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As shown in the figure, the power supply voltage remains unchanged, the range of ammeter is 0 ~ 3a, and the resistance R2 = 10 Ω
(1) When the switch S is off, the reading of the ammeter is 1.2A, calculate the power supply voltage; (2) when the switch S is closed, calculate the current indication of the ammeter when the slide P of the sliding rheostat is at the right end; (3) when the switch S is closed, calculate the minimum resistance of the sliding rheostat
As shown in the figure, the power supply voltage is 9V, the amperemeter indication is 0.3A, and the resistance R2 = 10 Ω. Calculate the resistance value of the resistance R1
1. Calculate the voltage of R2 resistor: U2 = IR = 0.3 * 10 = 3V
2. Calculate the voltage of R1 resistor: U1 = u-u2 = 9-3 = 6V
3. The current of series circuit is equal everywhere, and the resistance of R1: R1 = U1 / I = 6 / 0.3 = 20 Ω
The power supply voltage remains unchanged, the range of ammeter A is 0-3A, and the resistance value of resistor R2 is 12 Ω. Close the switch and move the sliding rheostat to the midpoint of ammeter 2A;
Move the rheostat to the maximum value. The ammeter is 1.5A. Calculate the maximum resistance and power supply voltage. R2 is connected in parallel with the rheostat. The total current is measured by the ammeter
Because R2 is in parallel with the rheostat, the total resistance of the two is 0.5r · 12 / (0.5r + 12) for the first time and R · 12 / (R + 12) for the second time
As shown in the figure, in the circuit, the power supply voltage U = 4.5V remains unchanged, the resistance R1 = 5 Ω, the maximum resistance of rheostat R2 is 20 Ω, the range of ammeter is 0 ~ 0.6A, the range of voltmeter is 0 ~ 3V, which is to protect the ammeter, and the resistance range of rheostat access circuit is ()
A. 2.5～10ΩB. 0～20ΩC. 2.5～20ΩD. 0～10Ω
It can be seen from the circuit diagram that R1 and R2 are connected in series, the voltmeter measures the voltage at both ends of R1, and the ammeter measures the current in the circuit. (1) when the resistance of the sliding rheostat in the circuit increases, the total resistance in the circuit increases, ∵ I = ur, ∵ the indication of the ammeter in the circuit decreases, and the indication of the voltmeter in parallel at both ends of R1 decreases, then the resistance of the sliding rheostat can be fully connected into the circuit, that is (2) when the indication of the voltmeter is 3V, the current in the circuit is I = u1r1 = 3v5 Ω = 0.6A, ∵ the range of the ammeter is 0 ~ 0.6A, ∵ the current in the circuit is I '= 0.6A, the resistance of the sliding rheostat in the circuit is the minimum, and the total resistance in the circuit is r = UI' = 4.5v0.6a = 7.5 Ω, ∵ the total resistance in the series circuit is equal to the sum of the partial resistances, ∵ the sliding rheostat in the circuit To sum up, the resistance range of sliding rheostat access circuit is 2.5 Ω ~ 20 Ω, so select C
RELATED INFORMATIONS
- 1. In the circuit as shown in the figure, the specifications of the two ammeters are the same. The ammeter has two ranges (0-0.6a and 0-3A). When the switch S is closed, the current flows through the resistance R1 and R2. If the pointer deflection angle of the two ammeters is the same, the ratio of R1 to R2 is () A. 1：5B. 5：1C. 1：4D. 4：1
- 2. The experimental equipment includes an ammeter with a range of (0 ~ 0.6A, 0 ~ 3a), a voltmeter with a range of (0 ~ 3V, 0 ~ 15V), a sliding rheostat (1a, 18 Ω) and a power supply (6V). If the resistance of about 6 Ω is measured with the above equipment, then: (1) in order to form the experimental circuit, in addition to the above equipment, it is necessary to______ One, at least______ (2) the range of current variation in the circuit is about______ (3) it is required that the pointer of ammeter and voltmeter should not exceed the range in the experiment, and the pointer of ammeter and voltmeter should be deviated from the middle line of the dial when measuring data for several times______ Range, voltmeter should be used______ Range
- 3. In the experiment of exploring the relationship between current and voltage, resistance, when exploring the relationship between current and resistance, we should () A. Adjust the sliding rheostat to keep the current in the circuit constant B. Adjust the sliding rheostat so that the voltage at both ends of different fixed resistor R remains unchanged C. Make the voltage at both ends of resistance R change in multiple D. The current in the circuit should be changed in multiple during each measurement
- 4. The resistor R1 and R2 are connected in series on the power supply with a voltage of 4.5V. The resistance of R1 is known to be 5 Ω, and the voltage at both ends of R2 is 3V. The total resistance in the circuit and the total resistance through R2 are calculated The resistance of an electric bell is 10 Ω. When it works normally, the voltage at both ends is 4V. Now it is connected to 9V power supply. In order to make it work normally, how much resistance should it be connected in series?
- 5. The resistance R1 and R2 are connected in series in the circuit, the voltage at both ends of R1 is 3V, R2 voltage is 9V, R1 + R2 = 600 Ω
- 6. If the voltage applied to both ends of a fixed value resistor increases from 6V to 10V and the current through the resistor changes by 0.1A, the electric power of the resistor changes () A. 1.6WB. 4.0WC. 0.4WD. 3.4W
- 7. There is a small bulb marked with "3V 1.5W" and resistor R1 in series in the circuit with 9V power supply. If the small bulb works normally for 1 minute, it is related to R1 in series? Chasing points There is a small bulb marked with "3V 1.5W" and resistor R1 in series in the circuit with 9V power supply. How to calculate the physical quantity related to R1 in series when the small bulb works normally for one minute?
- 8. In the series circuit, the rated voltage of a small bulb is 2.4V, and the resistance is 8 when the lamp is normally emitting. If there is only 3V power supply, if the bulb is normally emitting What is the resistance in series? (common series circuit)
- 9. There is a small light bulb. The resistance of the filament is 5 Ω when it lights normally, and the voltage required for normal operation is 2.5V. If we only have a 6V power supply, we need to make the small light bulb work normally______ The first resistance is______ The resistance in Ω
- 10. If the filament of a light bulb has been used for a long time, will the resistance of the filament increase or decrease? Why?
- 11. The title is "the circuit diagram of the experiment of measuring resistance by volt ampere method". In the diagram, there are ammeter (range 0 ~ 0.6A, 3a), voltmeter (range 0 ~ 3V, 15V), sliding rheostat (range of resistance value 0 ~ 12ohm), resistance Rx to be measured (about 6ohm, calculated as 6ohm) and power supply composed of three new dry batteries in series, I don't understand why the maximum current in the circuit is 0.75a, but the solution judges that the range of 0-0.6a should be selected. When the ammeter selects the range of 0-0.6, the maximum voltage at both ends of the constant resistance is 3.6V, but the solution judges that the range of 0-3v should be selected, Isn't that against the norm?
- 12. What is the resistance of 3A 0.6A ammeter? What about a 3V, 15V voltmeter?
- 13. The current is 1a and the voltage is 5V. How many resistances do you need to reduce the voltage to 4, 3, 2 and 1V
- 14. DC power supply 5V need resistance to step down to 4V, limit current in 4.5a need a few w several r resistance?
- 15. When the voltage at both ends of the resistor increases from 2V to 4V, the current intensity through the resistor changes by 0.25A, Then the resistance of the constant resistance ro is____ Ohm. The electrical power of the resistance ro increases____ w. This is to fill in the blanks!
- 16. Whether a small light bulb emits light depends on what? Rated voltage, rated current or resistance, or rated power
- 17. When exploring the relationship between the current and voltage on the resistance, the sliding rheostat changes the voltage at both ends of the light bulb, while the book says that the voltage of the small light bulb is larger, There's a lot of current in the circuit, but I feel it doesn't matter
- 18. How to find the resistance of light bulb?
- 19. A light bulb and a sliding rheostat are connected in parallel in a circuit to increase the resistance of the sliding rheostat. Does the light bulb turn on or dark?
- 20. To enable the rheostat to control the brightness of the bulb, should the rheostat be connected in series or in parallel with the bulb It controls the brightness of the light bulb