Draw a rough sketch of the pattern of the magnetic field lines due to:
$(i)$ current flowing through a circular coil,and
$(ii)$ a current-carrying solenoid.

(N/A) The magnetic field lines for a circular coil and a solenoid are described as follows:
$(i)$ For a circular coil: The magnetic field lines near the coil are nearly circular. As we move towards the center of the coil,the arcs of these circles become larger and appear as straight lines at the center. The direction of the magnetic field can be determined using the right-hand thumb rule.
$(ii)$ For a solenoid: The magnetic field lines inside the solenoid are parallel to each other,indicating a uniform magnetic field. Outside the solenoid,the field lines resemble those of a bar magnet,emerging from the North pole and entering the South pole.