To demonstrate repulsion/attraction between two conductors carrying current in opposite/same direction.
Consider two conductors (a and b) are carrying current Ia and Ib. Conductors are placed at a distance of d.
Conductor b experiences a force due to magnetic field of current carrying conductor a.
Magnetic field due to current in conductor a.
µ0 = 4π × 10-7 H/m
We get direction of magnetic field due to current Ia acting on conductor b is downward when we apply right hand thumb rule.
Force on b due to magnetic field Ba.
Consider two conductors (a and b) are carrying current Ia and Ib. Conductors are placed at a distance of d. Ia and Ib are in opposite directions.
a and b are two vectors. When we sweep our fingers from the direction of a to direction of b, direction of thumb gives direction of cross product (a x b).
Curl the palm of your right hand around the circular wire with the fingers pointing in the direction of the current. The right-hand thumb gives the direction of the magnetic field.