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Anonymous users2024-02-08Ohm's law is generally used to calculate resistance.
The expression of Ohm's law is current = voltage resistance, and the formula that requires resistance is resistance = voltage and current.
In this way, the resistance can be found by knowing the voltage at both ends of the appliance and the current in the appliance.
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Anonymous users2024-02-07The reference table of copper conductor resistance of commonly used products is as follows:
The resistance of the copper wire can be calculated according to the formula resistance = resistivity multiplied by the length of the cross-sectional area, as long as the resistivity of the copper wire is found from the relevant information, the resistance value can be calculated! When the resistivity of copper is 20 and 100 degrees Celsius, the resistivity is in and respectively. The mass of the copper wire = density multiplied by volume (volume = cross-sectional area multiplied by length, the copper wire resistance r with the density length of copper is calculated as follows:
Where: r is the conductor resistance, and the single hunger assignment: ohms.
l is the length of the conductor in meters.
is the resistivity of the conductor (also known as the specific resistance).
a is the cross-sectional area in square millimeters.
t is a constant. d is the nominal diameter of the wire in millimeters.
Resistivity: Resistivity (also known as specific resistance) is a physical quantity that measures the strength of a conductor to hinder the current. The lower the resistivity, the easier it is for the charge to pass through the conductor. The resistivity of copper wire is related to temperature.
Temperature coefficient of resistance:
The resistance of the wire depends on the ambient temperature of the rotten ear, and the relationship between resistance and temperature can be expressed by the temperature coefficient of resistance ā. At the temperature t, the coil resistance or wire resistance is calculated as follows:
Where: is the temperature coefficient of resistance.
r is the resistance of the coil or wire at temperature t.
R20 is the resistance of the coil or wire at a temperature of 20C.
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Anonymous users2024-02-06The formula for calculating the resistance is: r= l s.
Resistance (usually denoted by "R") is a physical representation of the amount of resistance a conductor has on an electric current. The greater the resistance of a conductor, the greater the resistance of the conductor to the current.
The resistance is defined by the ratio of the voltage u at both ends of the conductor to the current i passing through the conductor, i.e., r=u i. Therefore, when the voltage at both ends of the conductor is constant, the greater the resistance, the smaller the current passing through; Conversely, the smaller the resistance, the greater the current that will pass through. If you are interested, you can do an experiment by yourself.
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Anonymous users2024-02-05Formula for resistor calculation:
1) r = l s (where the resistivity of the resistor is determined by its own properties, l is the length of the resistor, and s is the cross-sectional area of the resistor).
2) Definition: r=u i
3) Total resistance in series circuit: r=r1+r2+r3+......Total resistance in a parallel circuit of rn(4): 1 R=1 R1+1 R2+......1 rn(5) find resistance by electrical power:
r=u²/p；r=p i Description: In physics, resistance indicates the magnitude of a conductor's resistance to an electric current. The greater the resistance of a conductor, the greater the resistance of the conductor to the current.
The resistance of different conductors is generally different, and resistance is a characteristic of the conductor itself.
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Anonymous users2024-02-04<>u，l，r，p。
Know the power, resistance, voltage and current. Know the power, voltage, and current to find resistance. Mastering the above formulas has been solved. “
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Anonymous users2024-02-03Resistance voltage and current, the unit of voltage is volts v, the unit of current is ampere a, and the unit of resistance is obtained
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Anonymous users2024-02-027 euros The need for wealth value can only help you get here.
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Anonymous users2024-02-01Your color ring resistor is a four-color ring.
Black0 Brown1 Red2 Orange3 Yellow4 Green5 Blue6 Purple7 Gray8 White9 Gold and silver indicate errors.
The meaning of each color ring is as follows:
The first color wheel: the first digit of the resistance value;
The second color ring: the second digit of the resistance value;
The third color wheel: power of 10;
The fourth color wheel: error representation.
Looking at the color wheel of your resistor, from left to right, my judgment is: orange blue black red = 36 + 10 = 36 ( 2%) The error is red, which means 2%.
You can also follow this mark.
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Anonymous users2024-01-31Rock collision resistance = resistivity x resistance length resistance cross-sectional area.
Resistance = 10 exp (-8) x 50 16 = x 10 exp (-8) ohm coarse source.
i.e. x 10-8 ohms.
Distinguish between the unit meter and the square millimeter, and the square millimeter and the square millimeter.
The longer the length, the greater the resistance, and the resistance value is proportional to the length, and the thicker the thickness, the smaller the resistance. It is inversely proportional to the cross-sectional product.
The resistivity of copper p= qmn2 m = ohm * square millimeter meters.
10-8 q .m2 m = 10-8 ohms * square meters.
Brown, black, red, silver is 10 * 10 2 = 1000 ohms, that is, 1k color ring resistance reading: >>>More
Diode. When the forward conduction is on, its forward resistance r = (forward voltage drop v) (forward current i), where the forward voltage drop v is basically unchanged when the diode is forward conductive (silicon tube approx; Germanium tube about. >>>More
According to the resistivity equation, if the earth fully plays the role of a conductor (the contact area of the positive and negative electrodes is very large), the magnitude of the resistance should be inversely proportional to the magnification (the cube is like this, the circle should be approximate), you can shrink the earth into a ball with a radius of 1 meter, add the electrodes to the poles of the ball, and measure the resistance r, then when the ball is enlarged to the size of the earth, the resistance will be r 6400000, which is very small. It's a pity that you can't magnify the connectors and energizing devices of the positive and negative electrodes to 6,400,000 times the original, so their resistance is infinitely larger than the resistance of the earth, and you electrify the earth like putting two ultra-thin needles on both ends of the ball, how much current do you say will pass through? Moreover, the voltage you add and the current you pass through are also insignificant to the earth, and the current is also restricted by many factors such as the geomagnetic field, so you can't electrify the earth! >>>More
For DC circuits, the resistance value of the capacitor is infinite. For AC circuits, the resistance value of the capacitance is related to the frequency of the AC and the capacitance of the capacitance, which is called capacitive reactance. There is a formula for calculating it.
The true value of Einstein's IQ was announced.
Thomas Harvey, a top physician at Princeton Hospital, quietly brought Einstein's brain home, soaked it in a disinfectant and antiseptic potion, then cured it with resin, cut it into about 200 pieces, and studied the brain himself, while also providing slices for the scientific community to study. >>>More