Two solenoids are each made of 2 000 turns of copper wire per meter. Solenoid I is 2 m long, while solenoid II is 1 m long. When equal currents are present in the two solenoids, the ratio of the magnetic field B_I along the axis of solenoid I to the magnetic field B_II along the axis of solenoid II, B_I/B_II, is A) 1/4. B) 1/2. C) 1. D) 2 E) 4.

Question

Quizplus · Accepted Answer

The magnetic field inside a long solenoid is given by $B = \mu_0 n I$, where $n$ is the number of turns per unit length, $I$ is the current, and $\mu_0$ is the permeability of free space. Since both solenoids have the same number of turns per meter and the same current, the magnetic fields inside them will be the same, regardless of their lengths. Therefore, the ratio of the magnetic fields is 1.

Two Solenoids Are Each Made of 2 000 Turns of Copper