Question

How similar or different are the magnetic field patterns produced by two bar magnets when:
a) Like poles are facing each other and b) when unlike poles are facing each other?

Answer 1

Hint: A magnetic field is a vector field which describes the movement of electric charges due to the presence of magnets in its near surrounding. These are represented by magnetic field lines. These also describe the strength of the magnetic force experienced by the charges.

Complete answer:
The magnetic force is the attraction or repulsion between electric charges due to their motion. This is a vector having both charge and direction. The strength or the ability at which the charges attract or repel depends on its magnetic field. The magnetic field lines can be measured as the magnetic field strength with SI units of ampere per meter, or in terms of magnetic flux density with SI units tesla. Magnetic field lines have certain properties, which are as follows:
1. They never cross each other.
2. The density of the field lines indicates the relative strength of the forces.
3. They always form closed loops, however, inside the magnet, they form straight lines.
4. The magnetic field lines start or emerge from the North Poles and ends or terminates at the South Pole.
Using the above nature as a guiding principle, we can draw the magnetic field lines of two bar magnets when
a) Like poles are facing each other as shown in the figure below:

 b) when unlike poles are facing each other as shown in the figure below:

Note:
Electrical and magnetic fields are interrelated. Variation of one affects the other, infact change in flux of one can produce the other. The sum of the two, i.e. magnetic and electrical forces result in a force called the Lorentz force.