Q.The Earth's magnetic field is completely horizontal at –
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🔒 Start your 14-day free trial to unlock the full solution →Concept understanding — Angle of Dip
What Is the Angle of Dip? A First Look
Imagine standing in an open field with a compass. The needle points roughly north — that much you know. But if you could watch that needle in three dimensions, you'd notice something else: in most places on Earth, the needle doesn't lie perfectly flat. One end tilts downward, as if it's trying to point into the ground. That tilt is the angle of dip (also called the magnetic inclination).
The Earth's magnetic field is not horizontal. It enters and exits the ground at an angle, depending on where you are. At the magnetic equator, the field runs parallel to the surface — no tilt. At the magnetic poles, it points straight down. Everywhere else, it's somewhere in between.
The Precise Definition
The angle of dip (δ) is the angle that the Earth's total magnetic field vector Btotal makes with the horizontal plane.
If you break the total field into two perpendicular components:
- BH — the horizontal component (parallel to the ground)
- BV — the vertical component (pointing into or out of the ground)
then the angle of dip is given by:
tanδ=BHBV
δ=tan−1(BHBV)
What the Sign Tells You
- Positive dip (BV downward): the north-seeking end of the needle dips below the horizontal. This happens in the northern hemisphere.
- Negative dip (BV upward): the north-seeking end rises above the horizontal. This happens in the southern hemisphere.
- Zero dip (BV=0): the field is entirely horizontal. This occurs along the magnetic equator.
At the magnetic poles, BH=0 and BV is maximum, so δ=90∘ — the needle points straight down (or up).
Why It Matters
The angle of dip is not a textbook curiosity. Navigators use it to correct compass readings near the poles. Geologists map it to understand the Earth's interior. And in your exams, it connects the components of the magnetic field in a clean trigonometric relation — one that lets you calculate any component if you know the total field strength and the dip angle. …
The Earth's field is horizontal wherever the angle of dip is zero, and that happens where the field lines run parallel to the surface, which is along the magnetic equator rather than the geographic one. …
The Earth's magnetic field is purely horizontal (dip angle = 0°) at the geomagnetic equator, and purely vertical (dip = 90°) at the geomagnetic poles.
The angle of dip is the angle the Earth's magnetic field makes with the horizontal. At the geomagnetic equator, the magnetic field lines run parallel to the Earth's surface, so the field has no vertical component — it is completely horizontal (dip = 0°). This should not be confused with the GEOGRAPHI …
- CBSE 2024Set ANNUAL1 markQ.If the horizontal and vertical components of earth's magnetic field are equal at a place, find the angle of dip.
›Reveal solutionSolution
tan(dip)=BV/BH; equal components give dip = 45°.
The angle of dip δ at a place is related to the horizontal (BH) and vertical (BV) components of the Earth's magnetic field by:
tanδ=BHBV
…
- CBSE 2023Set ANNUAL1 markMCQQ.The vertical component of earth's magnetic field at a place is sqrt(3) times the horizontal component. The value of angle of dip at this place is(1) 30 degrees(2) 45 degrees(3) 60 degrees(4) 90 degrees
›Reveal solutionSolution
The angle of dip is found from tan(dip) = vertical component / horizontal component of Earth's field.
…
- CBSE 2023Set ANNUAL1 markMCQQ.At a given place the horizontal and vertical components of earth's magnetic field are equal. The angle of dip at that place will be:(a) 0°(b) 45°(c) 60°(d) 90°
›Reveal solutionSolution
When the horizontal and vertical components of Earth's magnetic field are equal, the angle of dip is 45°.
The angle of dip δ at a place relates the vertical component BV and horizontal component BH of Earth's magnetic field by
tanδ=BHBV …
- CBSE 2023Set ANNUAL1 markMCQQ.In the magnetic meridian of a certain place, the horizontal component of earth's magnetic field is 0.26G and dip angle is 60°. The magnetic field of the earth at this location is -(a) 0.50G(b) 0.52G(c) 0.54G(d) 0.56G
›Reveal solutionSolution
B=BH/cosδ=0.26/cos60°=0.52 G.
…
- CBSE 2021Set A1 markMCQQ.The value of angle of dip at magnetic pole of the earth is (A) 0° (B) 90° (C) 45° (D) 180°
›Reveal solutionSolution
Angle of dip is 90° at the magnetic poles, 0° at the magnetic equator.
The angle of dip (inclination) δ is the angle the earth's total magnetic field makes with the horizontal. At the magnetic poles the field is entirely vertical, so a freely suspended dip needl …
- CBSE 2021Set A1 markMCQQ.If B is earth's magnetic field in magnetic meridian, δ is angle of dip, B_H is horizontal component of B and B_V is vertical component of B, then which of the following relations is correct? (A) B_H = B cosδ (B) B_V = B cosδ (C) B_H = B sinδ (D) B_V = B_H sinδ
›Reveal solutionSolution
Horizontal component B_H = B cos δ; vertical component B_V = B sin δ.
The earth's total magnetic field B makes an angle δ (the dip) with the horizontal. Resolving it:
BH=Bcosδ,BV=Bsinδ
…
- CBSE 2021Set OC1 markMCQQ.At the poles, the angle of dip is(a) 45∘(b) 30∘(c) 0∘(d) 90∘
›Reveal solutionSolution
The angle of dip is the angle the Earth's total magnetic field makes with the horizontal; at the poles the field is purely vertical.
The angle of dip δ satisfies tanδ=BHBV, where BV and BH are the vertical and horizontal components of the Earth's magnetic field.
…
- CBSE 2020Set 55/1/11 markQ.The magnetic field and angle of dip at a place on the earth are 0⋅3 G and 30∘, respectively. The value of vertical component of the earth's magnetic field at the place is ___________ .
›Reveal solutionSolution
The vertical component of Earth’s magnetic field is found using BV=Bsinδ, where B=0.3 G and δ=30∘. The result is 0.15 G.
The Earth’s magnetic field at any location has both horizontal and vertical components. The angle of dip (or magnetic inclination) δ is the angle that the total field B makes with the horizontal plane. If you imagine the total field vector pointing into the ground at an angle, its vertical part is simply the projection along the downward direction.
The relationship is purely trigonometric:
- Horizontal component: BH=Bcosδ
- Vertical component: BV=Bsinδ
Here, we are given the total field B=0.3 G (gauss) and the dip angle δ=30∘. We need BV.
- Write the formula for the vertical component:
BV=Bsinδ
- Substitute the given values:
BV=0.3×sin30∘
- Recall that sin30∘=21=0.5.
BV=0.3×0.5=0.15
- The unit remains gauss (G), since both B and BV are in the same unit. …
- CBSE 2020Set ANNUAL1 markMCQQ.In the magnetic meridian at a certain location, the horizontal component of earth's magnetic field is 0.16 G and angle of dip is 60°. The earth's magnetic field at this location is: (A) 0.32 G (B) 0.36 G (C) 0.18 G (D) 0.16 G
›Reveal solutionSolution
Using H=Bcosδ, the total field B=H/cosδ=0.16/cos60°=0.32 G.
…
- CBSE 2019Set ANNUAL1 markQ.Where on the surface of the earth is the vertical component of earth's magnetic field zero?
›Reveal solutionSolution
At the magnetic equator the field is entirely horizontal, so the vertical component BV=0 and the angle of dip δ=0.
The Earth's magnetic field at any point can be resolved into a horizontal component BH and a vertical component BV, related to the total field B and the angle of dip δ by
BH=Bcosδ,BV=Bsinδ
At the magnetic equator, the Earth's field lines run parallel to the surface (purely horizontal), so the angle of dip δ=0∘. Hence
BV=Bsin0∘=0 …
- CBSE 2019Set ANNUAL1 markMCQQ.The value of angle of dip at the earth's magnetic pole is -(a) 0°(b) 45°(c) 90°(d) 180°
›Reveal solutionSolution
Angle of dip at the magnetic poles = 90°.
The angle of dip is the angle the Earth's total magnetic field makes with the horizontal. At the magnetic poles the field is entirely vertical (horizontal component B_H = 0), so a dip needle points vertically an …
- CBSE 2019Set ANNUAL1 markQ.Define angle of dip. Write value of angle of dip at magnetic poles of earth.
›Reveal solutionSolution
Angle of dip is the angle earth's magnetic field makes with the horizontal; at the magnetic poles it equals 90 degrees.
Definition: At any place the earth's magnetic field can be resolved into a horizontal component (H) and a vertical component (V). The angle of dip (delta) is the angle by which the total field B dips below the horizontal, i.e. tan(delta) = V/H.
At the magnetic equator the field is purely horizontal, so V = 0 and delta = 0 degrees. …
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