The magnetic field lines inside a current carrying long solenoid are i

The magnetic field lines inside a current carrying long solenoid are in the form of

ellipse.
parabola.
hyperbola.
parallel straight lines.
This question was previously asked in
UPSC CDS-2 – 2021
Inside a current-carrying long solenoid, the magnetic field is strong and uniform. The magnetic field lines are parallel to the axis of the solenoid and are close to each other, indicating a uniform field. They are essentially parallel straight lines within the solenoid.
The magnetic field inside an ideal long solenoid is uniform and axial.
Outside the solenoid, the magnetic field is weak and spreads out. The magnetic field lines form closed loops, emerging from one end (North pole) and entering the other end (South pole), similar to a bar magnet, but the field is concentrated and parallel inside.