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What is the metal case of a flashlight equivalent to in a circuit?
Negative pole of power supply
As shown in the figure, if the current in the flashlight is 0.5A and the power supply is three dry batteries, the power of the small bulb of the flashlight is closest to () & nbsp;
A. 2.25WB. 0.75WC. 0.25WD. 9.00W
When three 1.5V dry batteries are connected in series, the voltage of power supply: u = 3 × 1.5V = 4.5V, the power of flashlight small bulb: P = UI = 4.5V × 0.5A = 2.25w
What is the voltage of a flashlight with two new dry batteries______ 5. If the resistance of the bulb is 10 Ω, the current passing through the filament is about 10 Ω when it normally emits light______ ．
∵ the total voltage in the series circuit is equal to the sum of the partial voltages, and the voltage of the flashlight power supply is u = 2 × 1.5V = 3V. According to Ohm's law, the current through the filament is I = ur = 3v10 Ω = 0.3A
RELATED INFORMATIONS
- 1. How many Ω is the resistance of the filament when the flashlight bulb is emitting? How many Ω is the resistance of the copper wire used in the experiment, so it can be ignored
- 2. It is proved that the total resistance is equal to the sum of the resistances in series circuit
- 3. Is it correct that total voltage divided by total resistance equals total current in series circuit
- 4. In a series circuit, the higher the resistance, the higher the voltage?
- 5. When exploring the relationship between fixed resistance and voltage at both ends in series circuit, is the resistance of sliding rheostat related to voltage? Why Is the greater the resistance of the sliding rheostat, the higher the voltage? Why? Is the higher the resistance of a constant value resistor, the higher the voltage at its two ends? But wouldn't that make the current smaller? (I mean change to another constant resistor)
- 6. In a series circuit, there are two consumers. If you add one more battery, what is the change of current? The consumer with high resistance adds more voltage than the consumer with low resistance What is the voltage applied by the appliance?
- 7. The voltmeter is connected in series with a resistor. Whose voltage is the measured voltage?
- 8. Here is a round pencil and a scale with division value of 1 mm. How to measure the diameter of the thin copper wire
- 9. How many kilos of copper wire is needed for 4km copper wire with a cross section of 25 square mm? (copper density = 8.9 times 10 cubic kg / M cubic) ↘
- 10. How to distinguish copper wire from aluminum wire? The original title is: how do you distinguish the following substances in your daily life? (one of them is: aluminum wire and copper wire)
- 11. The two dry batteries in the flashlight can only emit weak light after a long time. Take out the two dry batteries and measure them with a voltmeter. The voltage at both ends is close to 1.5V. Put them into the electronic clock and they can work normally. This phenomenon is explained by Ohm's law of closed circuit
- 12. The light bulb in the home circuit will be dimmed if it is used for a long time. The one that can make the light bulb brighter is a. replace it with a bigger light bulb. B. replace the dry battery of the flashlight C change to a new battery d change to a smaller bulb
- 13. Use a light bulb, a dry battery and a switch to make a self-made desk lamp. When the switch is off, the light bulb will be on. When the switch is closed, the light bulb will not be on. Draw the wrong circuit diagram Brother, help me. Please bring the picture Without a picture, please explain
- 14. Connect a dry battery, a small electric bead with a working voltage of 2.5V and a pencil lead with a length of 7cm to form a circuit as shown in the figure. Adjust the length of the pencil lead in the circuit just so that the small electric bead does not light up. Now you can strike a match and heat the pencil lead, and the small electric bead will light up later. Once the match goes out, the small electric bead will go out slowly. Here, the flame Like a switch, why can the flame play such a role?
- 15. When the dry cell voltage is increased from 1.5V to 3V, how to increase the potential difference to increase the battery voltage? In other words, how to increase the potential difference is related to the electric field strength, and what determines the electric field?
- 16. 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?
- 17. 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!
- 18. 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?
- 19. 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?
- 20. 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?