Which one of the statements given below is not correct ?

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Q: 71 (NDA-I/2010)

Which one of the statements given below is not correct ?

question_subject: 

Geography

question_exam: 

NDA-I

stats: 

0,13,27,12,8,7,13

keywords: 

{'magnetic meridian': [2, 0, 1, 1], 'relative permeability': [0, 0, 1, 0], 'geographical meridian': [1, 0, 1, 0], 'magnetic field': [0, 0, 0, 6], 'vertical plane': [0, 0, 2, 1], 'magnet': [0, 0, 2, 6], 'dimensionless quantity': [0, 0, 1, 0], 'axis': [0, 0, 0, 1], 'rotation': [1, 0, 0, 2], 'earth': [0, 1, 1, 1]}

Option 1: A vertical plane passing through the axis of a freely suspended magnet is called the magnetic meridian. This means that the magnetic meridian is a plane that aligns with the axis of rotation of the magnet. This statement is correct.

Option 2: A vertical plane passing through the axis of rotation of the Earth is called the geographical meridian. This means that the geographical meridian is a plane that aligns with the Earth`s axis of rotation. This statement is also correct.

Option 3: The degree to which the magnetic field can penetrate a medium is known as the relative permeability of the medium. Relative permeability is a measure of how easily a material allows a magnetic field to pass through it. This statement is correct as well.

Option 4: The relative permeability is not a dimensionless quantity. This statement is incorrect. Relative permeability is a dimensionless quantity and is represented by the symbol μr. It is the ratio of the permeability of the medium to the permeability of free space. Therefore, in this case, the correct answer should be "Alert - correct answer should be option 4".

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