Which one among the following correctly defines a unit magnetic pole in SI units ? It is the pole which when placed in air at a distance of

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Q: 17 (CDS-I/2012)
Which one among the following correctly defines a unit magnetic pole in SI units ? It is the pole which when placed in air at a distance of—

question_subject: 

Science

question_exam: 

CDS-I

stats: 

0,13,27,9,13,9,9

keywords: 

{'magnetic pole': [0, 0, 0, 1], 'si units': [0, 0, 0, 1], 'pole': [0, 0, 1, 5], 'similar pole': [0, 0, 0, 1], 'metre': [0, 3, 4, 3], 'unit': [0, 1, 5, 10], 'cm': [2, 0, 7, 20], 'm2': [0, 1, 0, 6], 'force': [0, 0, 0, 2]}

Option 1 states that a unit magnetic pole is defined as the pole which, when placed 1 foot away from an equal and similar pole in air, repels it with a force of 1 pound. This definition is incorrect. The SI unit system does not use pounds as a unit of force, and the distance of 1 foot is not consistent with the SI unit system.

Option 2 correctly defines a unit magnetic pole in SI units. According to this option, a unit magnetic pole is the pole which, when placed 1 metre away from an equal and similar pole in air, repels it with a force of 1 newton. This definition is consistent with the SI unit system, where the newton is the unit of force and the metre is the unit of distance.

Option 3 states that a unit magnetic pole is defined as the pole which, when placed 1 cm away from an equal and similar pole in air, repels it with a force of 1 dyne. This definition is not consistent with the SI unit system, as the dyne is not an SI unit of force.

Option 4 states that a unit magnetic pole is defined as the pole which, when placed 1 metre away from an equal and similar pole in air,