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What is the experimental principle applied in the experiment of measuring resistance by voltammetry?
The transformation of Ohm's Law (I = u / R) r = u / I
A student uses the circuit shown in the figure to measure the resistance of the small colored lamp (regardless of the influence of temperature on the resistance), and the line connecting the voltmeter in the figure is not drawn. In the experiment, close the switch, move the slide of the sliding rheostat, and get the ammeter and voltmeter indication as shown in the table below. According to the data in the table, answer the following questions. Current indication / A, voltage indication / V 0.303.0 0.40 2.0 0.50 1.0 (1) in the course of the experiment, the student______ (2) please connect the voltmeter to the circuit. (3) try to find the power supply voltage and the resistance of the small color lamp
(1) According to the analysis of the current data in the table, the current decreases gradually, which indicates that the resistance value of the sliding rheostat connected to the circuit is getting smaller and smaller, that is, the sliding rheostat moves to the right. (2) according to the voltage data in the table, when the current in the circuit increases, the indication of the voltmeter decreases, which indicates that the voltmeter is parallel at both ends of the sliding rheostat
As shown in figure (a), in the experiment of measuring the resistance of a small bulb, R 'is a sliding rheostat. (1) fill in two symbols in the circle, so this method is called______ (2) slide rheostat slide P is moved to change the resistance______ . when connecting the circuit, switch s should______ The slide should be in the______ (3) as shown in figure (b), R is the resistance to be measured, let R be about 3 Ω, use pen wire instead of wire to connect the components in figure (b) into a circuit (note that the wires do not cross and the component position does not move)
(1) It can be seen from figure (a) that the ammeter on the left is connected in series in the circuit, and the ammeter in parallel with the bulb is the voltmeter. The circuit diagram is shown in figure (a). This method of measuring voltage and current and measuring resistance is volt ampere method. (2) moving sliding rheostat slide P is to change the voltage at both ends of the bulb. When connecting the circuit, switch s should be disconnected, and the slide should be on the right side (3) according to figure (b), the power supply voltage is 1.5V × 2 = 3V, so the voltmeter should choose the range of 0 ~ 3V, the maximum current of the circuit is about I = ur = 3v3 Ω = 1a, then the ammeter should choose the range of 0 ~ 3a, the power supply, switch, resistance to be measured, ammeter and sliding rheostat are in series, the voltmeter and resistance to be measured are in parallel, the circuit diagram is shown in figure (b) The circuit diagram is shown in figure (b)
In the experiment of measuring electromotive force and internal resistance of battery by voltammetry, the error in the following precautions is ()
A. The old dry battery should be selected as the tested power supply to make the change of voltage indication more obvious B. the voltmeter and ammeter with smaller internal resistance should be selected C. when moving the slide of sliding rheostat, the sliding rheostat should not be short circuited to avoid current overload D When making U-I image according to the experimental data, a straight line should be drawn through as many points as possible, and the points not on the straight line should be evenly distributed on both sides of the line
A. According to u-e-ir, the old dry battery should be selected as the measured power supply to make the reading of the voltmeter change obviously, so a is correct; B. the internal resistance of the battery used in the experiment is very small. Compared with the power supply, the external connection method of the ammeter should be adopted. The error source of the external connection method of the ammeter is the shunt of the voltmeter. The larger the internal resistance of the voltmeter, the smaller the experimental error. The voltmeter with large internal resistance should be selected for the test C. when moving the slide of the sliding rheostat, the slide rheostat can not be short circuited, causing overload of the ammeter, so C is correct; D. when making U-I image according to the experimental data, a straight line should be drawn through as many points as possible, and the points not on the straight line should be roughly evenly distributed on both sides of the straight line
RELATED INFORMATIONS
- 1. When doing the experiment of measuring resistance by volt ampere method, the connection circuit is as shown in the figure. Please think about the following troubleshooting methods: (1) if the pointer of ammeter reverses after the switch is closed, this is because______ We can use it______ (2) if the voltmeter shows the number after the switch is closed and is close to the voltage value of the power supply, and the pointer of the ammeter hardly moves, this is because______ (3) if the ammeter shows the number after the switch is closed, the voltmeter does not______ (4) if the current indication is large after the switch is closed, it is because______ (5) if the current indication is very small after the switch is closed, adjust the slide of the sliding rheostat, and the pointer does not move because______ (6) (it can be seen from the experimental data) when the slide plate of the sliding rheostat is moved in the experiment, the indication of the two meters increases or decreases at the same time. If the opposite situation occurs, it is because______ ．
- 2. How to do the experiment of measuring resistance by voltammetry? If the control resistance does not change, why does it slide the slide to change the resistance? If the control voltage does not change, why does the voltmeter display different every time I'm going crazy What can t t do? It's too hard. I can't do it at all
- 3. Experimental principle and steps of measuring nonlinear resistance by voltammetry ditto Who will design a circuit diagram for measuring nonlinear resistance by volt ampere method Mainly the experimental principle, experimental steps!
- 4. There is an ammeter g with internal resistance Rg = 25 Ω and full bias current Ig = 3mA. How much resistance should be paralleled to refit it into an ammeter with a range of 0-0.6ma What is the internal resistance of the modified ammeter?
- 5. In the circuit shown in the figure, the power supply voltage is 3V, the resistance R1 is 10ohm, and the resistance is 5ohm. After the switch is closed, what is the connection mode between R1 and R2
- 6. R1 = 2 ohm, R2 = 6 ohm. After the switch is closed, the indication of ammeter is 4.8A Solution: the voltage ratio of resistance R1 and R2 Ratio of current through r1.r2 supply voltage The circuit is as follows: starting from the positive pole and passing through the switch, it is divided into two channels, one is R1, ammeter a, return to the negative pole, one is R2, ammeter a, return to the negative pole
- 7. The current of a certain lightning is about 2 × 10 fourth power a, the voltage is about 10 eighth power V, and the discharge time is about 0.001s. What is the point power of this lightning? How much energy is released
- 8. Two bulbs are connected in parallel in the circuit, the total resistance of the two lamps is 8 ohm, the resistance of the bulb L1 is 40 ohm, and the total current of the trunk circuit is 0.75 a 2) Current through bulb L1 3) current through bulb L2 4) resistance of bulb L2
- 9. [emergency] in the circuit shown in the figure, the voltage of the power supply is u, R is the constant resistance, the range of the voltmeter is 0 ~ 15V, and the range of the ammeter is 0 ~ 0.6A, Adjust the sliding rheostat, when voltage U1 = 12V, current I1 = 0.25A, when voltage U2 = 7.2V, current I2 = 0.4A 1. Power supply voltage U; 2. Resistance value of resistance R 3. In order to ensure the safety of the circuit, the sliding rheostat is connected to the resistance range of the circuit
- 10. An ammeter with a range of 100ua has a 100 ohm internal resistance and even dial scale. Now a 9900 ohm resistance is connected in series. If it is modified into a voltmeter, how many V is the range of the voltmeter
- 11. The principle of the experiment of measuring resistance by voltammetry is as follows______ In the process of connecting the circuit, the switch must be in the______ The slide of the sliding rheostat should be at the lowest resistance______ The main purpose of this is to avoid the interference in the circuit______ &After the power is turned on, first adjust the voltage at both ends of the small bulb to zero through the sliding rheostat______ For the safety of the equipment, the measurement should start from the rated voltage step by step______ Voltage, (fill in "up" or "down") to obtain several sets of data
- 12. All formulas and experiments, such as voltammetric resistance measurement For example: w = FS Important experiments. Voltammetric resistance and so on. Now
- 13. On the physical experiment to explore the relationship between resistance and current in the circuit In order to keep the voltage at both ends of the conductor unchanged, it is necessary to adjust the sliding rheostat to a larger value when replacing a larger constant value resistor in the experiment. Why and why?
- 14. In the experiment of studying the relationship between current, voltage and resistance, the purpose of using sliding rheostat in the circuit is two times
- 15. Use ammeter and voltmeter, measure the method of small bulb resistance to call voltammetry, what is the principle?
- 16. For the existing power supply with unknown voltage [voltage unchanged], one ammeter, one voltmeter, one sliding rheostat [known maximum resistance is R0] and one resistance Rx to be measured, There are two switches and several wires. Please draw two different schemes of measuring RX resistance according to the requirements, and write down the experimental steps and the process and expression of calculating Rx
- 17. When the switch is closed for the experiment, it is found that the voltmeter and ammeter show the number no matter how the slide rheostat is moved. What is the reason In the experiment of measuring constant resistance or measuring electric power of small bulb
- 18. In the circuit as shown in the figure, the power supply voltage does not change. When s is closed and the slide P of the sliding rheostat moves from left to right, the change of the indication of the three meters is () A. A bigger, V1 unchanged, V2 bigger B. a bigger, V1 smaller, V2 unchanged C. A unchanged, V1 smaller, V2 bigger D. a smaller, V1 bigger, V2 bigger
- 19. As shown in the figure, when the power supply voltage remains unchanged and the switch S is closed, when the slide P of the sliding rheostat moves from left to right, the change of the three meters is () A. V1 increases, V2 decreases, a increases, B. V1 decreases, V2 increases, a decreases, C. V1 remains unchanged, V2 increases, a remains unchanged, D. V1 remains unchanged, V2 decreases, a remains unchanged
- 20. R is the resistance box, V is the ideal voltmeter, when the resistance box is R1 = 2 ohm, the voltmeter reading is U1 = 4V, when the number of resistance boxes is R2 = 5 ohm, the number of voltmeters is U2 R is the resistance box, V is the ideal voltmeter. When the resistance box is R1 = 2 ohm, the reading of the voltmeter is U1 = 4V. When the number of resistance boxes is R2 = 5 ohm, the number of voltmeters is U2 = 5V