The rheostat is connected to a current source with a voltage of U = 6 V. The current in the rheostat is I = 0.5 A

The rheostat is connected to a current source with a voltage of U = 6 V. The current in the rheostat is I = 0.5 A, and the length of the wound nickel wire is L = 30 m. Determine the cross-sectional area S of the nickel wire. (Nickelin resistivity p = 0.40)

To determine the required cross-sectional area of the nickelin wire used, we use the equality: U / I = R = ρ * l / S and S = ρ * l * I / U.

Variables and constants: ρ – specific electrical resistance of nickelin (by condition ρ = 0.4 Ohm * mm2 / m); l is the length of the nickel wire used (l = 30 m); I is the current in the rheostat (I = 0.5 A); U is the voltage at the current source (U = 6 V).

Let’s make a calculation: S = ρ * l * I / U = 0.4 * 30 * 0.5 / 6 = 1 mm2.

Answer: The wire has a cross-sectional area of 1 mm2.