A current of 4 A flows through the conductor. The length of the conductor was doubled.

A current of 4 A flows through the conductor. The length of the conductor was doubled. The voltage between the ends of the conductor and the cross-sectional area did not change. What was the current in the conductor?

Let the resistance of a conductor of length l be R.

Ohm’s law for a chain section:
I = U / R (I – current, U – voltage between the ends of the conductor);
U = IR.

Since the resistance of the conductor with a constant cross-section is directly proportional to its length, then after increasing the length by 2 times, its resistance became equal to 2R, and the current strength was I1.

The voltage remains the same:

U = I1 * 2R.

Compare the right-hand sides of the stress equations:

IR = I1 * 2R;

I = 2I1;

I1 = I / 2 = (4 A) / 2 = 2 A.

Answer: 2 A.