Magnetic field lines can be entirely confined within the core of a toroid, but not within a straight solenoid. Why?

Explanation

To understand why magnetic field lines can be entirely confined within the core of a toroid but not within a straight solenoid, we can analyze the structure and properties of both devices.

### Step-by-Step Solution:

1. **Understanding the Structure**:
- A **toroid** is a doughnut-shaped coil of wire, where the wire is wound in a circular manner around a central core. The magnetic field lines in a toroid are confined within the circular path of the coil.
- A **straight solenoid** is a long coil of wire wound in a helical shape. It has two open ends, which means the magnetic field lines can extend outside the coil.

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