The strength of the magnetic field inside a long current-carrying straight solenoid is

In the below figure,$A$ and $B$ represent two straight wires carrying equal currents in a direction at right angles to the plane of paper inwards. Sketch separately the magnetic field lines produced by each current. Give a reason why the magnetic field at $K$ (mid-point of the line joining $A$ and $B$) will be zero.
What will be the effect on the magnetic field at $K$ if the current in wire $B$ is reversed?

$(i)$ $A$ compass needle gets deflected when brought near a current-carrying conductor. Why?
$(ii)$ What happens to the deflection of the needle when the current in the conductor is increased?

The direction of induced potential difference (induced current) is given by:

$(a)$ 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?

The following diagram shows two straight wires carrying current. Copy the diagram and draw the pattern of lines of force around them and mark their directions.