How can we find the direction of the magnetic field due to a straight current-carrying conductor?

Who proposed the principle of electromagnetic induction?

How can you show that the magnetic field produced by a given electric current in a wire decreases as the distance from the wire increases?

$AB$ is a current-carrying conductor in the plane of the paper as shown in the figure. What are the directions of the magnetic fields produced by it at points $P$ and $Q$? Given $r_1 > r_2$, where will the strength of the magnetic field be larger?

Name and state the rule to determine the direction of a force experienced by a current-carrying straight conductor placed in a magnetic field which is perpendicular to it. Name a device that uses a current-carrying conductor and a magnetic field.

Draw the pattern of magnetic field lines due to a current-carrying solenoid. Clearly mark the north and south poles in the diagram.