At which place Earth's magnetic field becomes horizontal ?
- A.Magnetic meridian
- B.Magnetic equator
- C.Geographical pole
- D.Tropic of Cancer
Correct answer
Explanation
The correct answer is B, Magnetic equator. On the magnetic equator the angle of dip is zero, so the Earth's magnetic field there is entirely horizontal.
The Earth behaves like a huge bar magnet. A freely pivoted needle, called a dip needle, shows the angle the field makes with the horizontal. This angle of dip is 0° on the magnetic equator, where the field lines run parallel to the ground, and 90° at the magnetic poles, where the field is vertical. Between them the dip grows steadily with magnetic latitude. Because the field is horizontal at the equator, its horizontal component there equals the full field strength.
A is wrong: the magnetic meridian is the vertical plane in which a compass needle rests; the field is horizontal in it only at the equator.
C is wrong: near the poles the field is close to vertical, the opposite of horizontal.
D is wrong: at the Tropic of Cancer the needle still dips at a clear angle below the horizontal.
Exam tip: angle of dip is 0° at the magnetic equator and 90° at the magnetic poles.
Practice Questions
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- A.wind vane
- B.wind rose
- C.barometer
- D.anemometer
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- C.polarization of light
- D.total internal reflection of light
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- A.Light wave
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- A.0-200 Hz
- B.20-20,000 Hz
- C.200-20,000 Hz only
- D.2,000-20,000 Hz only
Show answer
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