$A$ coil of insulated copper wire is connected to a galvanometer. What will happen if a bar magnet is held stationary inside the coil?

Draw the pattern of magnetic field lines associated with a current-carrying straight conductor. State how the magnetic field produced changes:
$(i)$ with an increase in current in the conductor,and
$(ii)$ with an increase in the distance from the conductor.

$(a)$ An electric current is passed in a horizontal copper wire from east to west. Explain your observations when a compass needle is placed $(i)$ below this wire,$(ii)$ above the wire. Draw inference from your observations.
$(b)$ List the factors on which the strength of the magnetic field due to a straight conductor carrying current depend. How should these be changed to decrease magnetic field at a point?

By increasing the number of turns $3$ times in a toroidal solenoid,the magnetic field:

$A$ current through a horizontal power line flows in east to west direction. What is the direction of magnetic field at a point directly below it and a point directly above it?

Draw the pattern of magnetic field lines due to a current-carrying solenoid. Clearly mark the north and south poles in the diagram.