Question

Isogonic lines on magnetic map represent lines of
A. zero declination
B. equal declination
C. equal dip
D. equal horizontal field

Answer 1

Hint: According to modern earth's magnetism theory, Earth has both geographic poles and magnetic poles. The magnetic poles of the earth magnetic field and the intensity of magnetic field varies from place to place. Total magnetic intensity has two components. One is the vertical component and the other is the horizontal component.

Complete answer:
The angle between the vertical component and horizontal component of the magnetic field is called dip at a particular location. The plane which is passing through magnetic poles at a certain place is called the magnetic meridian and the angle between these two planes is called the declination at that place. Declination varies from place to place. The dip angle lies in the magnetic meridian. Whereas declination is the angle between the two planes. Isogonic lines of the magnetic map represent the lines joining the places with the equal declination .

So, the correct answer is “Option B”.

Additional Information:
The angle between the vertical component and horizontal component of the magnetic field is called dip at a particular location. The plane which is passing through magnetic poles at a certain place is called the magnetic meridian and the angle between these two planes is called the declination at that place. Declination varies from place to place. The dip angle lies in the magnetic meridian. Whereas declination is the angle between the two planes. Isogonic lines of the magnetic map represent the lines joining the places with the equal declination .

Note:
In this question you are asked to find the use of isogonic lines on a magnetic map.
Dip angle will be 90 degrees at magnetic poles whereas zero at the equator.
There are different terms for the lines which join the places that have the same dip.