Answer question numbers (a)-(d) on the basis of your understanding of the following paragraph and the related studied concepts :
Oersted demonstrated that an electric current flowing through a conductor produces a magnetic field. The field so produced exerts a force on a magnet placed in the vicinity of the conductor. Ampere suggested that the magnet must also exert an equal and opposite force on the current carrying conductor. The direction of the force on the conductor depends upon the direction of current as well as the direction of magnetic field. Force acting on the conductor is found maximum when the direction of current is at right angles to the direction of the the magnetic field. In such a condition we can use a simple rule to find the direction of the force on the conductor Electric motor, electric generator, microphone, loudspeaker and measuring instruments etc. make use of current carrying conductors and magnetic fields.
How can you demonstrate that an electric current flowing through a conductor produces a magnetic field around it?

Explanation

A magnetic compass needle placed in the neighbourhood of current carrying conductor gets deflected from its north-south direction.