Describe in short an activity to:
$(i)$ demonstrate the pattern of magnetic field lines around a straight current-carrying conductor, and
$(ii)$ find the direction of the magnetic field produced for a given direction of current in the conductor. Name and state the rule to find the direction of the magnetic field associated with a current-carrying conductor. Apply this rule to determine the direction of the magnetic field inside and outside a current-carrying circular loop lying horizontally on a table. Assume that the current through the loop is anticlockwise.

(N/A) $(i)$ Take a battery $(12 \, V)$, a variable resistance (or a rheostat), an ammeter $(0-5 \, A)$, a plug key, and a long straight thick copper wire. Insert the thick wire through the centre, normal to the plane of a rectangular cardboard. Take care that the cardboard is fixed and does not slide up or down. Connect the copper wire vertically between the points $X$ and $Y$ in series with the battery, a plug, and a key. Sprinkle some iron filings uniformly on the cardboard. Keep the variable of the rheostat at a fixed position and note the current through the ammeter. Close the key so that a current flows through the wire. Ensure that the copper wire placed between the points $X$ and $Y$ remains vertically straight. Gently tap the cardboard a few times. Observe the pattern of the iron filings. You would find that the iron filings align themselves showing a pattern of concentric circles around the copper wire.
$(ii)$ When a magnetic compass is placed on these lines, it experiences a force in the direction of the magnetic field. Thus, the direction of deflection of the needle of the compass gives the direction of the magnetic field. Now, when the current is reversed, the direction of deflection of the needle also reverses. This shows that the direction of the magnetic field has also reversed. The rule is the Right-Hand Thumb Rule. It states that: "Imagine that you are holding a current-carrying straight conductor in your right hand such that your thumb points towards the direction of current. Then your fingers will wrap around the conductor in the direction of the field lines of the magnetic field."
For a circular loop lying horizontally on a table with anticlockwise current: By applying the Right-Hand Thumb Rule, the magnetic field lines inside the loop will be directed vertically upwards, and outside the loop, they will be directed vertically downwards.