![](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>)
The calculation of the voltage in the circuit with resistor diodes and light emitting diodes in series In 12V DC power supply circuit, 1K resistor, diode 4007 and a LED are connected in series, how much is the circuit current, how much is the voltage at both ends of the diode and the LED, and how much is the voltage at both ends of the LED Is the voltage drop of the diode the terminal voltage at both ends of the diode?
The voltage at both ends of LED is about 1.8V for red, 2V for green and 0.7V for common diode. Subtract the voltage of these two diodes from 12V and divide it by 1K resistance = the current of the circuit
I would like to ask 20, 18, 15, 12, 9 and 5 LED lamps in series, 5V voltage; how much resistance do they add?
It is used in the control of single chip microcomputer
I want to use SCM control, this is 5V voltage ah, ready to make a water lamp
If the voltage is 5V in series, it can't be done in parallel. Even for ordinary light-emitting diodes, the conduction voltage should be 2V, one in series plus 2V, and 20 in series. You can calculate the voltage by yourself. Parallel connection is feasible, but the power supply should have enough power to drive the current of the maximum 20 LED lights. According to the calculation of ordinary 20mA white LED, the conduction voltage is 3V, the current is 10mA, 5 LEDs, and the current limiting resistance is (5-3) / (5 * 10) = 40, According to this formula, calculate the number of current limiting resistors to be added, and take the standard value
RELATED INFORMATIONS
- 1. Using 5.5V voltage with 3V 20mA LED bulb resistance value Should I use a resistor with U / I = R (5.5 / 0.02 = 275), or a resistor with (input voltage output voltage) / current = (5.5-3) / 0.020 = 125 ohm, or some other resistor? Give me a value and the solution to this problem in the future,
- 2. How much resistance does it take to connect 1 LED (light emitting diode) in series with 24 V voltage
- 3. The voltage at both ends of the small bulb is 3.8V, and the current passing through is 0.3A. Within 10min, the current does work on -- J and consumes -- J's electric energy To get the formula, the process
- 4. If the light bulb is short circuited, does the voltmeter and ammeter show the number?
- 5. What is open circuit, short circuit, open circuit? How to know whether the bulb is short circuit or open circuit? What about the series connection of voltmeter? What about the parallel connection of ammeter? It's junior high school science knowledge
- 6. In the series circuit, a bulb short circuit or open circuit, how does the voltmeter and ammeter change, and in the parallel circuit, how does the ammeter and the voltmeter change
- 7. The ammeter is out of order. There is a voltmeter. How to measure the rated power of the bulb
- 8. When measuring the electric power of small bulb, considering that the ammeter and voltmeter have certain resistance, should the measured value of electric power of small bulb be larger than the real value
- 9. Xiaohong and Xiaowei have done the experiment of "measuring the electric power of small light bulb". There are two kinds of power supply (voltage is 6V), voltmeter, ammeter and sliding rheostat (a is marked with "50 Ω & nbsp; & nbsp; 2A", B is marked with "20 Ω & nbsp; & nbsp; It is known that the rated voltage of the two small lamps are 2.5 V and 3.5 V respectively, and the rated current is the same. They choose the equipment to carry out the experiment. Xiaohong connects the circuit correctly, connects a small lamp into the circuit, closes the key, moves the slide of the rheostat, and observes that the small lamp lights normally when the slide is near the midpoint. The ammeter shows the following As shown in the figure. ① during the experiment, the rheostat selected by Xiao Hong is______ (choose "a" or "B"), the rated voltage of the lamp she measured is______ V, rated current of______ Please calculate the rated power of Xiaohong and Xiaowei according to the relevant information______ (write the calculation process)
- 10. There is a small bulb of ammeter and voltmeter in series circuit Among them, the voltmeter measures the normal light of the small bulb The position of ammeter bulb is changed Write down what's going to happen next
- 11. When calculating the power of resistance and the current and resistance in closed circuit, why are the relevant formulas pure resistance If the non pure resistance does not conform to Ohm's law, please explain why
- 12. When a resistor is connected to a circuit, the consumed power is 110W. When 3C charge is passed, 330j of electric energy is converted into internal energy, then () A. The voltage applied to the resistor is 330vb. The current through the resistor is 1Ac. The power on time of the resistor is 3SD. The resistance value of the resistor is 110 Ω
- 13. Why is the total electric power divided by the supply voltage not equal to the circuit current in a series circuit? Why is the power divided by the voltage not equal to the circuit current?
- 14. How to calculate the total power when the current and voltage of three-phase electricity are known/
- 15. Current calculation of three phase electricity According to the formula P = 1.73ui Then the three-phase current is 98.110.105 respectively. How to calculate the power In addition, there is a 400v30kw51.4a generator. Does 51.4a mean that each phase can carry 51.4a current
- 16. When two resistors are connected in parallel, please tell us the distribution law of their current and electric power
- 17. In the home circuit, what is the device that shows how much electricity is used?
- 18. Problems in the chapter of home circuit in Physics There is a voltage of 220 V between the live line and the zero line, not between the zero line and the ground, and not between the ground and the ground. Why? It is said in the book that the zero line is connected to the ground, and then the ground is grounded. I don't quite understand. Who can explain this voltage. But isn't the home circuit AC? Can't the current pass through the zero line? At this time, it has no voltage? And, Is it OK to touch the zero line when you get an electric shock? Does the zero line also have current? It's better to have a circuit diagram to explain If the zero line forms a loop with the live line, why does it have no voltage and current
- 19. When the switch is closed, the light doesn't work, but the fuse is blown immediately. The reason for this phenomenon may be () A. There is an open circuit somewhere in the circuit B. connect one end of the switch to the neutral line and one end to the live line C. connect the switch to the neutral line D. the voltage in the circuit is too low
- 20. Exercises of physical circuit diagram in grade three of junior high school