The electromagnet winding is made of copper wire, the cross section of which is 0.05 mm2.

The electromagnet winding is made of copper wire, the cross section of which is 0.05 mm2. With a current strength of 15 mA, the voltage at its ends is 6 V. Determine how many meters of wire were used to make an electromagnet winding?

S = 0.05 mm2.

I = 15 mA = 0.015 A.

U = 6 V.

ρ = 0.017 Ohm * mm2 / m.

L -?

We express the length of the wire L from the formula that determines the resistance R of a cylindrical homogeneous conductor: R = ρ * L / S, where ρ is the resistivity of the material from which the conductor is made, S is the cross-sectional area of ​​the wire.

L = R * S / ρ.

We express the wire resistance R from Ohm’s law for a section of the circuit: R = U / I, where U is the voltage at the ends of the winding, I is the current in the wire.

The wire length L will be determined by the formula: L = U * S / ρ * I.

L = 6 V * 0.05 mm2 / 0.017 Ohm * mm2 / m * 0.015 A = 1176.5 m.

Answer: L = 1176.5 m of wire was used to manufacture the winding of the electromagnet.