![](data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 72 71" width="72"></svg>)
If the filament of a light bulb has been used for a long time, will the resistance of the filament increase or decrease? Why?
A: the resistance of the filament becomes larger. Because the filament is used for a long time, it will become thinner due to sublimation, and the resistance becomes larger
After the filament of a bulb is broken, if it is put on again, the resistance of the filament will become smaller and the brightness will become brighter; what is the impact of the smaller contact area at the contact point and the larger resistance?
I feel that the effect is that the light bulb breaks down soon,
When the filament of a bulb is broken and put on again, the resistance of the filament will be reduced and the brightness will be bright; the contact area at the contact point will be reduced and the resistance will increase the temperature in the bulb, and the interface will be easy to melt, enter the air, the filament will burn and the bulb will be damaged
After the filament of a light bulb is cut, its resistance will decrease. Why?
After the filament is broken, it can't light up. If the filament is overlapped together, it doesn't seem to change. In fact, most of the filament are not tight (I don't believe that the filament will move very weakly when I swing the good bulb at home). Therefore, it's impossible to completely connect the end-to-end, but one end is in the
RELATED INFORMATIONS
- 1. The rated voltage of a bulb is 2.5V. Now, how to connect it to a 6V power supply Rated power is 5W) small light bulb can normally light up
- 2. A 10 ohm resistor, a 3V voltage source, a 3A current source. Series. Power A 10 ohm resistor, a 3V voltage source and a 3A current source. In series, what is the power of the current source? (the current direction of the current source is the negative pole of the voltage source)
- 3. As shown in the figure, the specification of the small bulb is "6V & nbsp; 3.6W" (filament resistance does not change), close the switch, when the slide P of the sliding rheostat moves to the a end, the current indication is 0.6A; when the slide P moves to the B end, the voltage indication is 4V, then () A. The filament resistance of the small bulb is 6 Ω B. the power supply voltage is 10vc. The maximum resistance of the sliding rheostat is 10 Ω D. when the slide P is located at the B end, the power consumed by the sliding rheostat is 0.8W
- 4. In the experiment of "measuring the rated power of small light bulb", it is known that the power supply voltage is 6V, the small light bulb is marked with "3.6V", and the filament resistance is about 12 Ω. The equipment used is as shown in the figure. The range of 0-15v of voltmeter is broken, the range of 0-3v is in good condition, and other equipment is in good condition. Xiaoming has connected some equipment. (1) from the figure, it can be seen that he reasonably selects the range of 0-0.6a of ammeter, and he The reason for choosing this range is ⊙___ (2) adjust the slide of the sliding rheostat. The reading of the voltmeter shows that the small bulb can light normally, but he doesn't know how to connect the voltmeter. Please connect the voltmeter to the circuit correctly with the stroke line representing the wire, and answer___ (3) move the slide to ⊙ before closing the switch___ End (fill in: "left" or "right"), the purpose of doing so is ⊙___ (4) after closing the switch, adjust the slide P. when the small bulb lights normally, the indication of the ammeter is 0.3A, then the rated power of the small bulb is ⊙___ W．
- 5. When the voltmeter measures the voltage, the voltage of the two dry batteries is exactly 3V, and the two ranges of the voltmeter are 0 ~ 3 and 0 ~ 15. Which range should be selected?
- 6. When studying the relationship between current and resistance, the experiment is carried out with a fixed resistance of 5 Ω to make the indication of voltmeter 3 V, and then with a fixed resistance of 10 Ω A student didn't change the position of the slide vane of the sliding rheostat. After closing the switch, the voltmeter's indication will be () 3V (fill in "greater than", "less than" and "equal to"). Therefore, adjust the slide vane to () (fill in "left" or "right" note: reduce the resistance to the left and increase the resistance to the right), so that the voltmeter's indication will still be 3V (greater than) 3V; because the resistance and the sliding rheostat share voltage, the sliding rheostat resistance does not change, the resistance increases, the voltage will increase Adjust (to the right). Increase the resistance of the sliding rheostat, the voltage on the sliding rheostat will increase, and the voltage on the series resistance will decrease Why does the voltage of sliding rheostat increase when the resistance of sliding rheostat increases?
- 7. The electromotive force and internal resistance of three dry cells in series (electromotive force of each cell is about 1.5V and internal resistance is about 0.3 Ohm) shall be measured with ammeter and voltmeter, A ammeter: range 0.6 a, internal resistance 1 ohm. B ammeter: range 3 A, internal resistance 0.2 ohm. C voltmeter: range 3 V, internal resistance 30 Ka ohm. D voltmeter: range 6 V, internal resistance 60 Ka ohm. E sliding rheostat 0 ~ 1000 ohm, rated current 0.1 A. f sliding rheostat 0 ~ 20 ohm, rated current 2 A. g wire key ······Why choose d instead of C voltmeter? Why should the ammeter in the experimental circuit be connected internally instead of externally? Should the ammeter be connected internally when measuring electromotive force?
- 8. Connect the same two dry batteries in series or in parallel, and then connect the same small bulb. Is the brightness of the small bulb the same?
- 9. Excuse me, I use 2 dry batteries 3V power supply. 12 2.4v-3v current 20mA led parallel. How many ohm resistance? Can let 12 led normal light!
- 10. The fact that one dry cell and two dry cells are used to supply power to a small light bulb, which one is brighter, shows that changing what can change the current in the circuit?
- 11. 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
- 12. 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)
- 13. 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?
- 14. 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
- 15. 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
- 16. 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?
- 17. 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
- 18. 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
- 19. 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
- 20. As shown in the figure, the power supply voltage remains unchanged, the range of ammeter is 0 ~ 3a, and the resistance R2 = 10 Ω