Magnetic Field Pattern
Field Pattern around One Wire
The following magnetic field pattern will be observed for different direction of current flow through the wire. The direction of magnetic field is determined by Right Hand Grip Rule.
Note that the stronger the current flowing, the stronger the magnetic field strength produced.
Field Pattern between Two Wires
Flowing current in each wire produces its own magnetic field lines and interact with those produced by another wire, which resulting in a combined magnetic field lines.
Concepts for combined magnetic field:
Wires with like current
Like current means the current in the wires flow in the same direction.
① Field lines at opposite direction and equidistant from wires
=> Complete cancellation
② Field lines at opposite direction but not equidistant from wires
=> Field lines are further from the wire
③ Field lines at same direction
=> Field lines are closer to the wire
Likewise for unlike current where current in the wires flow in the opposite direction.
Field Pattern around a Flat Coil
It is same as the field pattern for unlike current.
Field Pattern around a Solenoid
Solenoid is several hundred turns on a coil.
By combining each field pattern formed by a flat coil, we will get a field pattern around a solenoid as shown below.
Its pattern is quite similar to that of a bar magnet. Thus, we can say that it acts like an electromagnet with two poles. The polarity of solenoid can be determined by Right Hand Grip Rule. However, unlike magnet, there are no field lines coming out from the side of solenoid.
To increase magnetic field strength in a solenoid, we can