Question

Why can’t two magnetic field lines cross each other? Draw magnetic field lines showing the direction of the magnetic field due to a current-carrying long straight solenoid. State the conclusion which can be drawn from the pattern of magnetic field lines inside the solenoid. 

Hint:

A solenoid produces a uniform magnetic field inside, making it useful as a magnet in various applications. The strength of the magnetic field can be increased by increasing the number of turns or the current.

Answer 1

F₂Why Magnetic Field Lines Don't Cross
Magnetic field lines cannot cross. If they did, it would mean the magnetic field has two directions at the same spot, which is impossible.

F₂Magnetic Field of a Long Straight Solenoid:
A solenoid is a coil of wire carrying current. Inside, the magnetic field is uniform and parallel, with straight field lines. Outside, the field resembles a bar magnet's, with north and south poles.

\[\text{Inside the solenoid:} \quad \text{Uniform magnetic field, parallel lines.}\] \[\text{Outside the solenoid:} \quad \text{Similar to a bar magnet's field, with loops.}\]

F₂Solenoid Magnetic Field Summary:
The magnetic field inside the solenoid is uniform, parallel, and its strength depends on the current and the turns per unit length.