![](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>)
How big is the resistance of 5 white LEDs in parallel 12V battery? Repair a small lamp. The resistance is burned
One is 20mA, five is 100mA, 12v-3.2v = 8.8v, 8.8v divided by 100mA, about 880 ohm 2W resistance
How much resistance does it take to connect 39 white LEDs (three in series and 13 in parallel) to 12V battery
3.3.6v
That is to say, an LED needs 10mA current. You have 39 LEDs, 39 * 0.01 = 0.195a, r = u / I = 12 / 0.195 = 301 Ω
Can three 1W led beads be directly connected to 12V battery of motorcycle in series? Do you need current limiting resistance? Or how much resistance
May I ask if a 1W LED lamp with a working current of 300mA and a rated voltage of 3.4V can be directly installed on a 12V battery on a motorcycle if three lamp groups are connected in series? Do you need a current limiting resistor? Or how much resistance,
It's all right, but you'll regret that the effect is too bad. I use three 3wled and all special reflective cups. The light is still too scattered. Now I use a 10W one, and I'm reluctant to use it. The main reason is that the concentration is not good. If I really want to install it, I must use a series resistor. The resistance value r = u / I = (12-3 * 3.4) / 0.3 = 6.2 Ω
Led highlight tube connected to 220 V power supply, with what kind of capacitance? How much resistance?
You need to know the current of your led, otherwise you can't choose. The capacitance is calculated according to 60mA "Ma" for each micro hair, and the resistance is calculated according to Ohm's law of a, I = u / R
You need to know the power of your led and calculate the current to choose,
RELATED INFORMATIONS
- 1. The voltage is 12 V and there is one 3mm diode. How much resistance do you need? How much resistance do you need for three diodes?
- 2. When a bulb works normally, the voltage is 12 V and the resistance is 24 Ω. If the power supply voltage is 36 V, in order to make the bulb work normally, it is necessary to When a bulb works normally, the voltage is 12 V, and the resistance is 24 Ω. If the power supply voltage is 36 V, in order to make the bulb work normally, what is the resistance in series?
- 3. The bulb marked "6V & nbsp; 3W" is connected in series with an 18 ohm resistor and connected to a 9V power supply. What is the actual power of the bulb?
- 4. A 5V 2W bulb L is connected in series with a 10 ohm resistor R1, and then connected to a stable voltage power supply. The lamp l will light normally L and resistor R2 are connected in series and connected to the same power supply. The power of bulb L is 0.5W. Calculate the resistance of R2
- 5. The bulb marked 12v6w is connected in series with a 36 ohm resistor on a 12V power supply. What is the actual power of the bulb? What is the power consumed by the resistor at this time?
- 6. There is a small light bulb, when it is connected in series with a 40 ohm resistor and connected to a 6 V power supply, it can light normally. The small light bulb can light normally for 5 seconds, and the current works for 1 joule Calculate the rated voltage of the small bulb,
- 7. When a small bulb is electrified for 2 minutes, it consumes 240 J of electric energy. Please draw the circuit diagram to calculate the electric power of the lamp
- 8. 1. A lamp consumes 1kW of electricity in 25 hours. What is the power of this lamp? 2. How many hours can a 220V 50W bulb work with 1000W of electricity 1. A lamp consumes 1kW in 25 hours. What is the electric power of this lamp? 2. How many hours can a 220V 50W bulb work with 1000W electric energy? (detailed solution process and formula are required) 3. How much energy is consumed by a 110 V, 100 W electric appliance working for one hour? If the power ratio of a and B dual-purpose electrical appliances is 4:1 and the power on time ratio is 2:1, what is the power consumption ratio?
- 9. 220 V power supply is connected in series with a 25 W bulb and a 40 W bulb. The actual power of the last two lamps is calculated and the calculation formula is listed
- 10. There is an electric lamp, which consumes 100 watts when connected to the power supply. Connect it in series with another resistor and then connect it to the same power supply. The power consumed by the resistor is 9 watts. The strategy of bulb consumption at this time is proposed
- 11. In the circuit shown in the figure, R1 = 30 Ω, R2 = 10 Ω. After the switch S is closed, the indication of ammeter A is 0.4A. Calculate the power supply voltage, the current through R2 and the current in the main circuit
- 12. A physics problem: there are four resistances, R1 = 1, R2 = 2, R3 = 3, R4 = 4, e = 4V, r = 0.2, total current ——R1——R3—— | | | ——R2——R4—— | | ——||————— R1 and R3 are in one branch, R2 and R4 are in one branch, that is to say, they are connected in series and then in parallel, and there is another line between R1 and R3 and between R2 and R4 The general circuit diagram is like this. The lines in the diagram are all connected Is the middle line useless?
- 13. Why is it that if the voltage indication number is zero, the circuit of the measured part is short circuited
- 14. What is the electromotive force of the power supply equal to the voltage between the two poles of the power supply when the power supply is open Such as the title Why is it not the voltage between the two poles of the power supply when the circuit is connected?
- 15. When the power supply is connected to the circuit, the potential difference between the two ends of the power supply is equal to, less than and greater than the electromotive force of the power supply Such as the title
- 16. Is electromotive force equal to supply voltage
- 17. The b value of triode is the parameter reflecting the ability, which is () a voltage control voltage B current control voltage C voltage control current D current control current
- 18. 1. If the external resistance of the ideal current source increases gradually, its terminal voltage () A. Gradually increase B. gradually decrease C. D. constant Better explain why
- 19. What is the difference between voltage source and current source? Voltage source and current source are the same power supply. I don't know the difference between them. Please answer in detail. Thank you!
- 20. How to judge whether the circuit is short circuit or open circuit from the presence of voltmeter and current indication Students said that in the series circuit, the small light bulb is not on. When the ammeter in series with the small light has a number, the small light is not normal. If the ammeter has no number, it means that the small light is OK. Is he right? Explain it. Thank you