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In the circuit shown in the figure, the power supply voltage remains unchanged. There may be faults in resistance R and lamp L. before and after the key s is closed, the position of ammeter pointer remains unchanged. The correct judgment in the following is () A. If lamp L does not light up, only resistance R is short circuited. B. If lamp L does not light up, only resistance R is open circuited. C. If lamp L lights up, only resistance R is short circuited. D. if lamp L lights up, only resistance R is open circuited
A. B. if the lamp L does not light up, it may be short circuit or open circuit of lamp L. if the lamp is short circuit, after closing the switch, the power supply will be short circuit, and the ammeter will burn out, so it is out of the question; if the lamp is open circuit, there is no indication of ammeter before and after closing the switch, and the pointer position remains unchanged, so it is possible, so the description in AB is out of the question; C, D, if the lamp L lights up, it means that only the resistance fails, and it is impossible It is an open circuit, because the resistance open circuit can not light up when the switch is closed, so it can only be the resistance R short circuit, so C is correct, which is in line with the meaning, D is wrong, which is not in line with the meaning
In the circuit shown in the figure, the power supply voltage remains unchanged, and R is the constant value resistor. When the switch is closed, the small bulb L marked with "8V & nbsp; 8W" just lights up normally; if the constant value resistor R remains unchanged, replace l with another small bulb marked with "8V & nbsp; 4W". After the switch is closed, the actual power consumed by the small bulb when it works ()
A. Greater than 4wb. Equal to 4wc. Less than 4WD. Cannot be determined
According to the formula r = u2p, when the voltage is the same, the greater the electric power is, the smaller the resistance is; therefore, the resistance of "8V 8W" bulb is higher than that of "8V 8W" According to Ohm's law, the current in the circuit becomes smaller and the voltage at both ends of the resistance R becomes smaller, ∵ the total voltage in the series circuit is equal to the sum of the partial voltages, and the voltage of the power supply remains unchanged, ∵ at this time, the voltage at both ends of the bulb becomes larger, greater than 8V According to P = u2r, at this time, the electric power of the bulb becomes larger, greater than 4W
In the circuit shown in the figure, the power supply voltage remains unchanged. There may be faults in resistance R and lamp L. before and after the key s is closed, the position of ammeter pointer remains unchanged. The correct judgment in the following is ()
A. If lamp L does not light up, only resistance R is short circuited. B. If lamp L does not light up, only resistance R is open circuited. C. If lamp L lights up, only resistance R is short circuited. D. if lamp L lights up, only resistance R is open circuited
A. B. if the lamp L does not light up, it may be short circuit or open circuit of lamp L. if the lamp is short circuit, after closing the switch, the power supply will be short circuit, and the ammeter will burn out, so it is not appropriate. If the lamp is open circuit, there is no indication of the ammeter before and after closing the switch, and the pointer position remains unchanged, so it is possible, so the description in AB is not appropriate. C. D. if the lamp L lights up, it means that only the resistance is faulty, and cannot be replaced It can be an open circuit, because it is impossible for the front lamp to light when the switch is closed, so it can only be a short circuit of resistance R, so C is correct and D is wrong
RELATED INFORMATIONS
- 1. The lamp and a resistor R are connected in series and then connected in a circuit with voltage of U. the current flowing through the lamp is I, and the electric power consumed by the lamp is?
- 2. A light bulb is marked with "4V, 4W". After it is connected in series with a constant resistance R, it is connected into the circuit with the power supply voltage of 6V. When the switch is closed, measure the A bulb is marked with the words "4V, 4W". After it is connected in series with a constant resistance R, it is connected to the circuit with the power supply voltage of 6V. When the switch is closed, the measured power consumption of R is 2W. At this time, the bulb does not light normally. Regardless of the influence of temperature on the resistance value of the bulb, calculate: 1 the resistance value of the constant resistance R, 2 the incident electric power of the bulb
- 3. In order to explore the "relationship between electric power and resistance", Li Ming found two lamps L1 and L2 with the rated voltage of 6V. He connected the two lamps in series and started the experimental exploration according to the circuit shown in the figure. After closing the switch, he saw that the lamp L2 was slightly luminous, while the lamp L1 was almost not luminous. Then the relationship between the resistance R1 and R2 of the two lamps, and the rated power P1 and P2 of the two lamps was established (not applicable) Consider the change of filament resistance value with temperature) () A. R1＞R2，P1＞P2B. R1＜R2，P1＜P2C. R1＞R2，P1＜P2D. R1＜R2，P1＞P2
- 4. 1. Two resistors with the same organization are connected in series first and then in parallel, respectively in the circuit with the same voltage. What is the ratio of the total power of series and parallel?
- 5. The bulb and a resistor are connected in series to the power supply. The power of the lamp is 81w, and the power of the resistor is 9W. If the lamp is directly connected to the power supply, it will light normally Calculate the rated power of the lamp
- 6. Without changing the power supply voltage, please design a circuit diagram to change the brightness of the bulb
- 7. 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
- 8. 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?
- 9. How to find the resistance of light bulb?
- 10. 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
- 11. As shown in the figure, the light bulb L is marked with "6V 3W", and the power supply voltage remains unchanged. When the switch is closed, the resistance of the sliding rheostat connected to the circuit is 4 Ω, and l lights normally, the power supply voltage is 0_____ 5. If the total power consumed by the circuit is 3.2w by changing the position of slide plate P of the sliding rheostat, then the actual power of the small bulb is___ W A graph is a series
- 12. In order to explore the relationship between current and resistance, Xiao Ming replaced the 10 ohm resistance between a and B with 20 ohm resistance as shown in Figure 8. After closing the switch, the next operation should be () A. Record the indication of ammeter and voltmeter B. Move the sliding rheostat to the right C. Move the sliding rheostat to the left D. Increase the number of batteries appropriately B, why.
- 13. The specification of an electric iron is "220 V & nbsp; & nbsp; & nbsp; 110 W". Please answer the following questions: (1) what is the normal working current of the electric iron? (2) What is the resistance of the electric iron? (3) How much heat does it produce when it is electrified for 10 minutes at rated voltage?
- 14. When exploring the relationship between the current on the resistance and the voltage at both ends, what should be kept unchanged?
- 15. The resistance of a conductor is directly proportional to the voltage at both ends of the conductor and inversely proportional to the current passing through the conductor Why wrong? How to understand the relationship between resistance, voltage and current? Don't use books. It's suitable for multiple choice questions
- 16. Is the statement "when the resistance of a conductor is constant, the current is proportional to the voltage"? Those who are right should pay attention! I thought it was right, but the answer is wrong! I wonder if it should be said that when the resistance of a conductor is constant, the current in the conductor is proportional to the voltage at both ends of the conductor! I want to win your opinions,
- 17. In the experiment of studying the relationship between current, voltage and resistance, what is used to control the current in the circuit
- 18. 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
- 19. If the voltage U and the resistance R are doubled simultaneously in a circuit, how will the power change? P = the square of (2U) divided by 2R Why is the square of (2R) divided by R
- 20. How does the change of resistance of sliding rheostat affect the change of voltage This is the eighth edition of Zhejiang Education Press. May I ask why the voltage of sliding rheostat in the circuit (series or parallel) changes? Why does the resistance of constant value resistor not change but affect the voltage? Does sliding rheostat affect the current, resistance and voltage? Another question: which factors are related to the brightness of the bulb? Current, voltage or resistance? There must be a lot of additional points!