![](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 internal resistances of small range ammeter g, ammeter A and voltmeter V are RG, RA and RV respectively A. RG＜RA＜RVB. RV＜RA＜RGC. RA＜RG＜RVD. RG＞RV＞RA
Because the ammeter is refitted into a voltmeter and needs series resistance, RV > RG & nbsp; & nbsp; because the ammeter is refitted into an ammeter and needs parallel resistance, RG > RA, the relationship between the resistance values of the three is: RA < RG < RV & nbsp; then a is wrong, B is wrong, C is correct, D is wrong, so C is selected
How to change a 12 volt 40 Amp dry cell into 12 volt 1 amp?
Do you want to increase the circuit or resistance
I think so
For a battery, the voltage is 12V, which is constant
But the current is not fixed, because the current depends on the resistance. I = u / R
First of all, you need to determine which consumer you want to supply 1 ampere of current, and then add one more resistor in series to make the total resistance of the circuit reach 12 ohm (if your consumer's resistance is greater than 12 ohm, you don't have to do so), so as to meet your requirements
For reference only
R2 is a sliding rheostat of 0 to 20 ohm. After closing K, the reading of voltmeter is 12V, and that of ammeter A1A2 is 0.5A and 1.5A
Calculate the resistance value of resistance R1
Resistance value of sliding rheostat access circuit
The ratio of heat released by R2 and R1 at the same time
---R2------
---R1----A1-----
A2
-----V----------
------K --- power supply-----
A2 should be on the trunk road. The following calculations are based on A2 on the trunk road. If not, skip T ^ t
R1r2 is connected in parallel, V is used to measure the power supply voltage, so u = 12V
A1 measures the current of R1, so R1 = u / I1 = 12 / 0.5 = 24 ohm
A2 measures the main circuit current, so the current passing through R2 is 1a, R2 = 12 ohm
Parallel circuit Q2: Q1 = I2: I1 = 1:0.5 = 2:1
Is the actual power of an electrical appliance working at rated voltage equal to the rated power
be equal to
No, it's lower than the rated power, because the circuit and the appliance itself will consume part of the electric energy
Theoretically, it is equal to, but there is allowable deviation value. If it exceeds the deviation value, it is unqualified.
1: What is the significance of measuring the surface resistivity and volume resistivity of ceramic materials?
2: What is the relationship between the resistivity of ceramic materials and the type and technology of ceramic materials?
The volume resistance is the quotient of the DC voltage applied between the two electrodes placed on the opposite surfaces of the specimen and the steady-state current flowing between the two electrodes
Volume resistivity is the quotient of DC electric field strength and steady-state current density in insulating materials, i.e. volume resistance per unit volume. Volume resistivity can be used as a parameter for selecting insulating materials. The resistivity changes significantly with temperature and humidity. Volume resistivity measurement is often used to check whether the insulating materials are uniform, Or it can be used to detect those conductive impurities that can affect the quality of materials and cannot be detected by other methods
Surface resistance is the quotient of the voltage applied between two electrodes on a surface of a sample and the current flowing between the two electrodes after a certain period of time
The surface resistivity is the quotient of DC electric field strength and linear current density of the surface layer of insulating material, that is, the surface resistance per unit area. The surface resistivity is not a parameter to characterize the characteristics of the material itself, but a parameter related to the surface pollution characteristics of the material, Therefore, the surface resistance can only be measured approximately, and the measured surface resistance mainly reflects the degree of surface contamination
Who knows how much work is equal to 1000 cal heat? Why? The key is how to convert cal and Joule?
CAL is card, 1 card is equal to 4.2 Joule, 1000 card = 4.2 * 10 ^ 3 Joule, 1 large card = 1000 card
220V voltage, 1kW power, several ampere current
Pure resistance load, current is 1000 △ 220 = 4.54a
Non pure resistance load, current greater than 4.54a
How many rated voltage and rated power does an electrical appliance have? What about the actual voltage and power
If the frequency changes, the rated voltage and rated power will also change. For example, the rated voltage of an electrical appliance is 220 V / 50 W at 50 Hz and 240 V / 55 W at 60 Hz. The actual power varies with the voltage. Assuming that the resistance of the electrical appliance is not affected by the temperature, w = u & sup2 / R, The higher the square of the voltage, the higher the power
Electrical insulating materials in China refer to the materials with volume resistivity
According to the national standard gb2900.5, the definition of insulating material is "the material used to insulate the device electrically", that is, the material that can prevent the current from passing through. Its resistivity is very high, usually in the range of 10 ^ 9 ~ 10 ^ 22 Ω· M
One thousand watt hours = 3.6 × 10 ^ 6 joules, two kilowatt hours = how many joules
=1kWh*2=3.6*2*10^6J
RELATED INFORMATIONS
- 1. The voltage at both ends of a conductor is 12 volts, and the current intensity passing through it is 0.9 amperes, so that the current intensity passing through it is 0.6 amperes, and the voltage applied at both ends of it should be more than 10 amperes
- 2. There is an ammeter with an internal resistance of 1 ohm and a measuring range of 1 A. if you want to expand the measuring range to 5 A, what kind of resistance should be connected? Is it in series or in parallel?
- 3. How many kilowatts of electrical appliances can 4 square millimeter copper wire use
- 4. How many catties of 16 square single strand copper core wire per meter How many jin copper per meter of 16 square single strand copper core wire?
- 5. What is converted from chemical energy to electrical energy?
- 6. Does nuclear power plant convert chemical energy into electrical energy?
- 7. Energy conversion in the process of nuclear power generation What is the energy conversion process of steam turbine in the process of nuclear power generation?
- 8. How much heat does one degree of electricity produce
- 9. How many joules is a large calorie?
- 10. How many kcal is 5000 kJ?
- 11. If the internal resistance Ra of the ammeter is 0.03 ohm and the internal resistance RV of the voltmeter is 2 kiloohm, the resistance R to be measured is about 1.5 kiloohm, and the internal and external connection methods have small error
- 12. In the circuit shown in the figure, the power supply voltage remains unchanged, R1 = 10 Ω. When the switch S is closed and the slide P of the sliding rheostat is in the middle point, the indication of the ammeter is 0.3A; when the slide P is moved to the rightmost end, the indication of the ammeter is 0.2A. Then the power supply voltage is 0.3A______ 5. The maximum resistance of sliding rheostat is______ Ω．
- 13. A circuit composed of a resistor, a power supply and an ammeter in series, The indication of the ammeter is 0.12A; if a 10 ohm resistor is connected in series in this circuit, the indication of the ammeter is 0.1A. Calculate the voltage of the power supply and the resistance in the original circuit
- 14. As shown in the figure, given the resistance R1 = 3 Ω, R2 = 6 Ω, the indication of ammeter A is 0.6A, then the indication of ammeter A1 is 0.6A______ .
- 15. If the indication of the ammeter increases by 4 times, R? Ohm resistance should be given Such as the title Better have an explanation
- 16. Measure the resistance with missing meter method, from the positive pole to the resistance RO and then to Rx, ammeter, switch to the negative pole, RX and RO are connected in parallel, and Rx resistance value is calculated with known power supply voltage ro resistance value
- 17. In the circuit shown in the figure, both ammeter and voltmeter are ideal ammeter. If resistance R1 is open circuit, the following statements are correct () A. The current indicates that the number becomes smaller; B. the voltage indicates that the number becomes larger; C. the power consumed by R3 becomes larger; D. the power consumed by the circuit in the power supply becomes larger
- 18. What can an ammeter measure besides the current?
- 19. What do the poles and zeros of a filter mean
- 20. The physical layer is the foundation of all networks. How many volts are used to represent 1, how many volts are used to represent 0, and how long does a bit last for microseconds?