![](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 conductor made of a material is 50m long and 4mm ^ 2 in cross section, and its resistance is zero Ω, what is the resistivity of the material?
The formula of resistance is r = ρ L / s, so ρ = RS / L = 5x0.0004/50 = 0.00004 ohm. M
Resistance = resistivity * conductor length / cross-sectional area,
R=ρ*l/S，
ρ=RS/l=5*4/50=0.4Ω*mm^2/m
Power consumption: 25W, how many kwh per hour
1 kilowatt hour = 1 kilowatt hour = 1 000 watt hour. That is to say, 1000 Watt equipment can use 1 hour. So 25 Watt can use 40 hours. Every hour is 1 / 40 kilowatt hour, that is 0.025 kilowatt hour
What is the maximum transmission distance under the condition of 220 V AC power supply, 2.5 M2 copper conductor and 100 W power load?
The normal working voltage drop of load should not be less than 15%. It is equivalent to 220x15% = 33 v. so the voltage drop of each wire should not be greater than 33 / 2 = 16.5 v. the allowable resistance of wire is equal to 16.5 V divided by 0.45 current = 36.7 ohm. The resistance is 2.5 square of 36.7 ohm
In the case of long-distance transmission, the power transmitted is p, the voltage transmitted is u, and the resistivity of the conductor used is p,
If the cross-sectional area is s and the total length is l, the power consumed by the transmission line is? And the power obtained by the user is?
The resistance is inversely proportional to the area and directly proportional to the length, and R = PL / s
Delivery current I = P / u
Then thermal power loss q = I ^ 2R = P ^ 2PL / (u ^ 2S)
The power obtained by the user is p '= p-q
How many kilowatts per hour does 3000 watts consume?
3 degrees
How much power does the computer power supply have at 220 V / 4A / 50 Hz
P = u * I = 220V * 4A = 880W, this is the input power of your power supply. Generally, the efficiency of switching power supply is about 90%, so the output power P (output) = P (input) * 90% = 880W * 90% = 792w
If two kinds of voltage (220 V and 11 V) are used to transmit the electric power, the power loss of the transmission line, the length and resistivity of the conductor are the same, the ratio of the cross-sectional area of the conductor is calculated
Suppose the transmission power is 220W,
Then the current ratio of the two is 1:20, the resistance of the former is 220 Ω, and the resistance of the latter is (11 / 20) Ω,
The ratio of resistance is 400:1
Because the resistance ratio is inversely proportional to the cross-sectional area of the conductor, the cross-sectional area ratio of the two conductors is 1:400
According to: r = ρ L / s and P = u / R, the ratio of the cross-sectional area of the line = the inverse ratio of the voltage = 11 / 220 = 1 / 20
1/400
1:400
1：400
Five houses, each with a 36 watt energy-saving lamp for 12 hours, how much electricity does it consume? (1000 Watt lamp consumes 1 kilowatt hour)
Hurry!
5×36×12=2160Wh
1000 × 1 = 1000WH = 1 degree
2160wh = 2.16 degrees
In a certain rating of 220 v.40 W, 220 v.60 w incandescent lamp, the incandescent lamp is connected in series with 220 V power supply, and then light?
Bright 40 watts
For long-distance transmission, the transmission power is p, the transmission voltage is u, the cross-sectional area of the transmission line is s, and the power loss of the line is △ P. if the voltage is increased to 10u, then ()
A. When △ SD is 0.01 times of the original transmission line, the transmission line power loss can still be reduced if △ SD is unchanged
A. According to P = UI, if the transmission voltage is increased to 10 times of the original, the transmission current will become 110. So the power loss is p = I2R = 1100 △ P, so a is correct. B. if the voltage loss on the transmission line is △ u = IR, the voltage loss will become 0.1 times of the original, so the voltage at the user end will not be 10 times of the original, so B is wrong. C. the transmission current will become 110. So the power loss is p = I2R = △ P, So the resistance changes to the original 100r, from R = ρ ls, the area decreases to the original 0.01s, so C is wrong; D, the loss of power is △ P = (PU) 2R, the voltage increases to 10u, so p can be increased to 10p, the loss of power remains unchanged, so D is correct, so ad is selected
RELATED INFORMATIONS
- 1. How many kilowatt hours does an 800 Watt appliance consume?
- 2. In order to connect a "220V 1000W" electric furnace to a 110V power supply, the power consumed is still 1000W, which can be used 2. In order to connect a "220V 1000W" electric furnace to a 100V power supply, the power consumption is still 1000W, the method that can be adopted is () A. Cut 1 / 2 of the electric furnace wire into the circuit B. The electric furnace wire is folded in half and connected to the circuit C. The electric furnace wire is divided into three equal parts, and then connected to the circuit in parallel D. Cut off 3 / 4 of the furnace wire and connect it to the circuit
- 3. 9. As shown in the figure, an electrified straight wire is vertically placed in a uniform magnetic field with magnetic induction intensity of 1t, and there are a and B on the circle with radius r centered on the wire There is a picture in this question. The elder brother and elder sister will ask me to pass the picture to you
- 4. Electric car battery is 60V ~ bought an inverter is 12V to 220V ~ want to use the battery in the electric car without dismantling the electric car, what's the way
- 5. If the mass of a bundle of copper wires is 4.45kg and the wire specification is 2mm, what is the length of the bundle
- 6. As shown in the figure, the length of each side of square wire frame ABCD is l, the mass of AB side is m, and the mass distribution is uniform, and the mass of other sides is not included. The total resistance of wire frame is R. the CD side is connected with smooth fixed rotating shaft OO ', and the wire frame can rotate freely around the OO' axis. The whole device is in a uniform magnetic field with magnetic induction intensity of B and vertical downward direction The results show that: (1) the quantity of electricity Q passing through the cross section of the wire in time t; (2) the magnitude and direction of Ampere force on the AB side at the lowest point; (3) the tensile force on the AB side at the lowest point; (4) the heat generated in the wire frame in time t
- 7. The total voltage and current of resistor R1 and R2 in series are 6 V and 1.2 A, respectively The total voltage and current of resistor R1 and R2 in parallel are 2.4 V and 2 a respectively. Calculate R1 and R2
- 8. 380V angle connected electric heating tube, a total of 72kw. Motor a total of 17kw. How many currents? How thick copper wire?
- 9. The maximum current that can be measured by an ammeter is 10mA. When the voltage at both ends of a resistor is known to be 8V, the current passing through it is 2mA. If a voltage of 50V is added to the resistor, can the ammeter be used to measure the current passing through the resistor? Please give your reason by calculation
- 10. A bulb is marked with 220 V 100 W. B bulb is marked with 220 V 40 W. A and B are connected in a 220 V circuit in series. What is the voltage ratio between the two ends of the lamp Such as the title
- 11. How many amperes and watts can a 220 V square copper wire carry? What about 380 V? I heard that when the power is more than several kilowatts, the copper wire should be doubled
- 12. The power is 100 watts, and the power consumption is 10 hours a day. How many kilowatt hours a day do you consume?
- 13. For the resistance coil with uniform thickness, the cross load area of the resistance wire is 2mm2 square, and the resistance rate is 1.1 times 10 to the negative sixth power ohm M A voltage of 4.4V is applied to both ends of the coil, and the current passing through it is measured to be 0.8A
- 14. 10. - 16-25-35-50-70-95 square meters of cable wiring to use how much copper nose What is the size of copper nose for 10,16,25,35,50,70,95 square cable connection
- 15. The rated power of refrigerator is 70W, the power consumption is 0.5kw.h/24h, and the rated power of TV is 65W
- 16. What is the resistivity of 700m copper wire? What is the resistivity of 700 meters copper wire? How much current can 10 square copper wire bear at most? What is the maximum current that a 700 meter copper wire can pass?
- 17. The size of a household electric iron is 220 V 800 W. it can generate J heat and use kwh electric energy after 10 minutes of normal operation
- 18. What kind of wire should be used to install a 15kw motor Is it OK to use 6 square meters or more?
- 19. The voltage at both ends of a conductor is 3V, the current passing through it is 0.3A, and its resistance is 10 Ω. When the current passing through the conductor is 0.5A, its resistance is Ω
- 20. The rated voltage is 220 V, the power is 40 W, and the resistance is calculated