How can the strength of a magnetic field produced by a solenoid be increased?

The strength of a magnetic field produced by a solenoid can be increased by increasing the size of the current. Increasing the current increases the size of the magnetic field which increases the number of turns in the coil. So the magnetic field has greater strength than a coil with fewer turns. And the strength of the magnetic field can be increased by creating an iron core, to do this place a piece of iron in the solenoid.