What happens to the deflection of the compass needle placed at a point near a current-carrying straight conductor:
$(a)$ If the current is increased?
$(b)$ If the direction of current in the conductor is changed (reversed)?
$(c)$ If the compass is moved away from the conductor?

(N/A) The deflection of the compass needle increases because the strength of the magnetic field produced by the conductor is directly proportional to the magnitude of the current flowing through it.
$(b)$ The direction of deflection in the compass needle changes (reverses) because the direction of the magnetic field lines around the conductor is reversed when the direction of the current is reversed.
$(c)$ The deflection of the compass needle decreases because the strength of the magnetic field decreases as the distance from the current-carrying conductor increases.