Ans:
A coiled wire, wound closely and neatly into a cylinder shape, is called a solenoid, as you can see in the picture.
The magnetic field created by a solenoid is just like the field produced by a bar magnet. In other words, one end of the solenoid acts like a North Pole, while the other end acts like a South Pole. Inside the solenoid, the magnetic field lines run in straight and parallel lines, which means the magnetic field is the same at every point inside the solenoid.
How strong this magnetic field is depends on two things: the number of turns in the solenoid (how many times the wire goes around the cylinder) and how much current is flowing through it. If you increase either the number of turns or the current, the magnetic field gets stronger.