Fill in the following blanks with suitable words :

(a) The lines of……………. round a straight current-carrying conductor are in the shape of…………………

(b) For a current-carrying solenoid, the magnetic field is like that of a………………………….

(c) The magnetic effect of a coil can be increased by increasing the number of…………………, increasing the…………, or inserting an…………….. core.

(d) If a coil is viewed from one end and the current flows in an anticlockwise direction, then this end is a pole.

(e) If a coil is viewed from one end, and the current flows in a clockwise direction, then this end is a………………….