1. Magnetic Field in a Solenoid
When a solenoid (coil of wire) has a current passing along it there is a magnetic field produced inside. The strength of this field depends on a few factors including the size of the current, the number of turns per metre and also the magnetic permeability.
2. Magnetic Field around a wire
You should be aware of the right hand grasping rule that shows the direction of the magnetic field around a wire. Here I explain how you can also calculate the magnitude of this field.