How to measure the DC resistance of 20 ℃ conductor of cable ≤ Ω / km? By the way, what's the difference between metal plating and non metal plating? Can you use a multimeter to measure the resistance?

Use DC resistance tester to measure the resistance value of the ambient temperature, and then multiply it by the correction factor, which is the DC resistance of 20 degrees. Generally, the resistance of metal plating is larger than that of metal plating. The multimeter has not tried to estimate it, or there is no need to purchase special instruments

How to determine the resistance of cable when calculating short circuit current? Is there a formula

This is quite complicated, which is related to the material, structure and temperature of the cable. Single core copper wire can be estimated as follows: the calculation formula of copper wire resistance R with length of & nbsp; L & nbsp; is as follows: & nbsp; & nbsp; & nbsp; where R & nbsp; is conductor resistance, unit: Ohm, L & nbsp; & nbsp; is conductor length, unit: meter ρ & nbsp

The resistance of the wire is 4 Ω. Now it is evenly stretched to twice of the original, and the resistance becomes () Ω
Step by step solution

16 Ω. First of all, if it is twice as long, the resistance will be twice, that is 8 Ω. Second, because it is elongated, the diameter of the wire will become half. Similarly, if the resistance is doubled again, that is 16 Ω

The resistance of a wire is 10 ohm. Fold it in half for three times, and how much ohm is the resistance after tightening it

R = ρ L / s, where ρ is the resistivity, l is the length of the material and S is the area
After one fold, ρ remains unchanged, l becomes L / 2, s becomes 2S
It becomes L / 4, 4S after twice and L / 8, 8s after three times,
Therefore, R '= ρ (L / 8) / (8s) = (ρ L / s) / 64 = R / 64 = 10 / 64 = (5 / 32) Ω

How to measure the DC resistance of 20 ℃ conductor of cable ≤ Ω / km? By the way, what's the difference between metal plating and non metal plating? Can you use a multimeter to measure the resistance?