State the form of magnetic field lines around a straight current--++carrying conductor.

State qualitatively the effect of inserting an iron core into a current-carrying solenoid.

Name the rule for finding the direction of magnetic field produced by a straight current-carrying conductor.

What is the other name of Maxwell’s right-hand thumb rule?

State whether the following statement is true or false:

The magnetic field inside a long circular coil carrying current will be parallel straight lines.