1. The Earth's magnetic field is primarily generated by:
a) Magnetic rocks in the crust
b) Movement of molten iron in the outer core
c) Gravitational forces of the Sun and Moon
d) Movement of molten iron in the inner core
Answer: b) Movement of molten iron in the outer core
The Earth's magnetic field is generated by the dynamo effect caused by the movement of molten iron and nickel in the Earth’s outer core.
2. The imaginary line connecting the magnetic north and south poles is known as:
a) Axis of rotation
b) Magnetic meridian
c) Equatorial line
d) Geographical meridian
Answer: b) Magnetic meridian
A magnetic meridian is the imaginary line that joins the magnetic north and south poles and represents the direction of the Earth’s magnetic field at a place.
3. Which of the following terms refers to the angle between geographic north and magnetic north?
a) Magnetic declination
b) Magnetic intensity
c) Magnetic inclination
d) Dip angle
Answer: a) Magnetic declination
Magnetic declination is the angle between true north (geographic) and magnetic north, and it varies by location and time.
4. What is the approximate location of the magnetic north pole (as of recent observations)?
a) Constant near the geographic north pole
b) Fixed in Siberia
c) Constant near the Arctic Circle in Canada
d) It keeps shifting over time
Answer: d) It keeps shifting over time
The magnetic north pole is not fixed and shifts due to changes in the Earth’s magnetic field. It has recently been moving from Canada towards Siberia.
5. Which instrument is used to measure the Earth’s magnetic field and its components?
a) Barometer
b) Magnetometer
c) Seismograph
d) Altimeter
Answer: b) Magnetometer
A magnetometer is an instrument used to measure the strength and direction of magnetic fields, including Earth's geomagnetic field.
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6. Which of the following best describes the Earth's magnetic field?
a) Uniform in intensity across the globe
b) Stronger at the equator than at the poles
c) A static magnetic field with fixed poles
d) A dynamic magnetic dipole field, stronger at the poles
Answer: d) A dynamic magnetic dipole field, stronger at the poles
The Earth’s magnetic field is not uniform. It behaves like a giant magnetic dipole tilted with respect to the rotational axis and is stronger at the poles than at the equator.
7. What is the primary source of the Earth's magnetic field according to the dynamo theory?
a) Magnetic rocks in the crust
b) Solar winds
c) Flow of electric currents in the outer core
d) Ions in the ionosphere
Answer: c) Flow of electric currents in the outer core
The magnetic field arises due to the flow of electric currents generated by the rotating metallic fluid (iron and nickel) in the outer core, which is known as the dynamo effect.
8. What is Paleomagnetism?
a) Study of magnetic fields in animals
b) Study of solar wind impact on Earth's magnetism
c) Study of ancient magnetic fields preserved in rocks
d) Study of present-day changes in Earth's magnetic poles
Answer: c) Study of ancient magnetic fields preserved in rocks
Paleomagnetism involves analyzing the magnetic record in rocks that formed in the past, providing evidence of past magnetic field directions and pole shifts.
9. What is the current rate of movement of Earth's magnetic north pole?
a) 50 km per year uniformly
b) 9 km per year towards Canada
c) 9 km per year towards Russia
d) Static and does not move
Answer: c) 9 km per year towards Russia
Currently, the magnetic north pole is shifting eastwards from Canada to Russia at approximately 9 km per year, though the rate may vary.
10. Which of the following is not an implication of the shifting magnetic field?
a) Disruption in compass-based navigation
b) Aurora Borealis appearing at different latitudes
c) Complete vanishing of Earth’s atmosphere
d) Confusion in migratory bird navigation
Answer: c) Complete vanishing of Earth’s atmosphere
While magnetic field shift affects navigation, communication, and auroral zones, it does not cause the Earth’s atmosphere to vanish. However, loss of the magnetic field (e.g., if Earth’s core cooled) could gradually expose Earth to solar radiation..
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