What is the formula for calculating resistivity?

What is the formula for calculating resistivity?

According to r = ρ (L / s), the formula of resistivity can be deduced
ρ=RS/L
p=RS/L
According to the influence factors of resistance in the experimental edition of new education, junior middle school students understand r = ρ (L / s), among which the resistivity of the corresponding material is ρ. The calculation formula of resistivity is deduced: ρ = RS / L, that is, the resistance value per unit area and length of conductor
A bulb with rated voltage of 220 V is connected to the lighting circuit, which can emit light normally. The current passing through it is measured to be 0.5 A, and the resistance of the bulb in normal operation is calculated
∵ the rated voltage of the bulb is 220 V, and the current passing through the bulb is 0.5 a when the bulb lights normally. The resistance of the bulb when it works normally is: r = UI = 220 V 0.5 A = 440 Ω. A: the resistance of the bulb when it works normally is 440 Ω
A copper wire with cross section of 0.10mm2 is 1.2m long. When a voltage of 0.6V is applied at both ends of the copper wire, the current passing through the copper wire is 0.1A, then the resistivity of the copper wire is______ .
According to Ohm's law, r = UI = 0.60.1 Ω = 6 Ω. According to resistance law, r = ρ ls, then resistivity ρ = RSL = 6 × 0.1 × 10 − 61.2 = 5 × 10 − 7 Ω· M
How to calculate resistivity
Resistance R = ρ L / S
Where ρ is the resistivity
L is the length of resistance (usually wire)
S is the sectional area
Measure the resistance, and then calculate the resistivity according to the formula. The resistivity is related to the material of the resistance
How many ohms is the resistance of a 220 V / 100 W bulb when its rated current is at that time
P=U*U/R
R = 48400 / 100 = 484 ohm
400KW motor distance 300m I want to choose how large cable, please help me see my calculation formula is correct
If I want to calculate the voltage drop of the two parallel lines, I = 0.0139 U / r i = 0.0138 U / R I / r = 0.0138
You can choose the cross section of the cable according to the allowable voltage loss. However, because the conductor has not only resistance but also reactance (mainly inductive reactance for low voltage) under AC condition, it is better to calculate and look up the table as follows: 1. Select the cable according to the long-term continuous current (safe current carrying capacity)
There's not that much current, is there
How to calculate resistivity
The resistivity of semiconductor is measured by DC four probe method. The test principle is: when four metal probes are aligned in a straight line and pressed on the semiconductor material with a certain pressure, the potential difference V (as shown in the figure) is generated between the two probes when the current I passes between the two probes 1 and 4
An electric appliance is marked with 220 V, 100 W, its resistance is 484 ohm, the teacher is r = U2 / P, the square of R = 220 / 100 = 484 ohm, why
To do this, the circuits must be in parallel
The basic formula: 100W / 220 V = 0.455 a, 220 V / 0.455 a = 484 ohm. If the formula is connected, 220 V / (100 W / 220) = 484, the formula is removed (): 220 / 100 * 220 = 484, and further simplified: 220 * 220 / 100 = 484, that is 220 square / 100 W
How much cable is required for 60kW power?
The normal working current of 60kW is between 110-120a. You can use 3 * 50 + 1 national standard copper wire or 3 * 70 national standard aluminum wire. Of course, if the distance is long, you can add another model, that is, copper wire uses 70 aluminum wire and 95 aluminum wire. If you want to buy non-standard wire cheaply, you need to add a model to buy it. You can go to my space to have a look at the relevant knowledge. There are contents in this aspect
If you use 35, it will definitely get hot. You can try one first. If it gets hot, you can use another 35
Simple calculation of resistivity
Myelin sheath is composed of multiple layers of lipid substance, myelin, which has great resistance. It is known that frogs have myelin nerve, and the thickness of myelin sheath is only about 2 μ m, but its resistance per square centimeter perpendicular to the current direction is as high as 1.6 × 10 ^ 5 Ω. If the contact resistance between myelin slices is not calculated, the resistivity of myelin can be calculated
According to the formula: r = ρ L / s, ρ is the resistivity, l is the length, s is the cross-sectional area
There are: 1.6 × 10 ^ 5 Ω = ρ × 2 × 10 ^ (- 6) m / [1 × 10 ^ (- 4) m ^ 2]
ρ=8.0×10^6 Ω.m
You have to understand!