1-why charged particle has to be in motion to define magnetic field? 2-will magnetic force exert any force on a static charge?(as in the static test charge in electric field) 3-A line from my book reads- " If a magnetic monopole (individual magnetic charge) were available, we could define magnetic field B in a similar way as electric field." What would be similar in magnetic field and electric filed if individual magnetic charges actually existed?
- Because of the answer to 2.
- No. This is what distinguishes a magnetic field from an electric field. In an electric field a charge experiences a force (proportional to its charge), whether it's stationary or moving. In a magnetic field a charge experiences a force only if it's moving.
- Up until sixty years or so ago, most physicists did define magnetic field strength in terms of the forces on a magnetic pole. The pole was sometimes approximately realised in practice as one pole of a ball-ended magnet. The magnetic field from a single pole obeys an inverse square law, like an electric field from a point charge (but, if you're using a ball-ended magnet – and there's no alternative in practice! – the law doesn't hold inside the magnet itself!)