NCERT Solutions Curiosity Chapter 13 .3.3 Magnetic field of the Earth — In-text Questions
Book page 21713 Updated on2026-09-05
Q1.
Does the magnetic field of the Earth have any role in sustaining life on Earth?
Answer
Yes — it acts as a protective shield around the whole planet.
The chain of reasoning runs like this:
Molten iron moving in the Earth's core is believed to be the origin of Earth's magnetic field, which is why the Earth behaves like a giant magnet and a freely suspended magnet settles in a fixed direction.
Earth is constantly hit by tiny, high-energy particles from space — cosmic rays from far across the universe and the solar wind from the Sun.
These particles can damage the atmosphere and reduce the ozone layer, which would let in more harmful ultraviolet rays.
The magnetic field pushes many of these particles away from the Earth, so the atmosphere — and therefore life — stays safe.
High-energy particles arriving from the Sun and from deep space are turned aside by Earth's magnetic field before they can reach the atmosphere.
Why it happens: The particles in the solar wind and in cosmic rays carry electric charge, and a magnetic field changes the path of a moving charged particle. So the field does not have to stop them — it only has to bend them around the planet, and that is enough.
Q2.
But, how is life supported and sustained on Earth?
Answer
Not by any single thing. Life is sustained by the constant exchange between four systems — the atmosphere, the hydrosphere, the geosphere and the biosphere.
The four Earth systems, each feeding the others. A change forced on any one of them travels round the circle.
Air, water and sunlight. The atmosphere holds the oxygen that humans, animals and plants use for respiration. In sunlight, plants take carbon dioxide from the air and water from the soil and prepare food by photosynthesis, releasing the oxygen that respiration needs. The greenhouse effect keeps the temperature just high enough for water to stay liquid; water vapour forms clouds, brings rain and snow, and refills rivers, lakes and groundwater.
Soil, rocks and minerals. The geosphere provides soil rich in nitrogen and potassium — nutrients that come from the slow breakdown of rocks and the remains of plants and animals — along with salt, coal, oil and metals such as iron and copper.
Living things. In the biosphere, plants make food, animals eat plants or other animals, and decomposers break down dead matter and return the nutrients to the soil.
Why it happens: Every one of these is a loop, not a one-way supply. Oxygen released by plants is used by animals, whose carbon dioxide goes back to plants. Water that leaves the ocean returns as rain. Nutrients taken from the soil are returned by decomposers. Because the materials cycle rather than run out, life can continue indefinitely on a planet of fixed size.