Draw a diagram to show how a magnetic needle deflects when it is placed above or below a straight conductor carrying current,depending on the direction of the current in the conductor.

(N/A) The diagram is as shown in the figure.
Consider a wire connected to a battery such that current flows through it. Place a magnetic compass directly over a horizontal wire. The needle points north when there is no current $(I = 0)$,as shown in Fig. $(a)$.
When a current is passed towards the north,the needle deflects towards the east,as shown in Fig. $(b)$.
When the current is passed towards the south,the needle deflects towards the west,as shown in Fig. $(c)$.
When the compass is placed directly below the wire,the direction of the needle's deflection is reversed.
Since a magnetic needle can be deflected only due to the presence of a magnetic field,it can be concluded that a magnetic field is produced around the current-carrying wire.