Question

Two long ideal solenoids (with radii 20 mm and 30 mm, respectively) have the same number of turns of wire per unit length. The solenoid is mounted inside the larger, along a common axis. The magnetic field with in the inner solenoid is zero. The current in the inner solenoid must be:

a. two-thirds the current in the outer solenoid
b. one-third the current in the outer solenoid
c. twice the current in the outer solenoid
d. half of the current in the outer solenoid
e. the same as the current in the outer solenoid

Answer 1

The current in the inner solenoid is zero and is the same as the current in the outer solenoid.

Step-by-step explanation:

To determine the ratio of the current in the inner solenoid to the current in the outer solenoid, we can use the formula for the magnetic field inside a solenoid. The magnetic field inside a solenoid is given by the equation B = μ₀nI, where B is the magnetic field, μ₀ is the permeability of free space, n is the number of turns per unit length, and I is the current. Since the magnetic field inside the inner solenoid is zero, the current in the inner solenoid must also be zero. Therefore, the current in the inner solenoid is zero and the correct answer is (e) the same as the current in the outer solenoid.

Answer 2

Answer: The current in the inner solenoid is the same as the current in the outer solenoid.

The correct option is e

Explanation: Please see the attachment below