Magnetic Field of the Earth (13.3.3) — "Our Home: Earth, a Unique Life Sustaining Planet"

1. 13 marks

   Why does the chapter say the Earth 'behaves like a giant magnet,' and what is believed to be the origin of this magnetic field?

   Hint. This links back to a fact from Grade 6 about suspended magnets, and a Grade 8 fact about what's moving deep inside the planet.

   ✦ In Curiosity Grade 6, students learnt that a freely suspended magnet always settles in a fixed direction — this happens because the Earth itself behaves like a giant magnet, so any nearby magnet aligns with Earth's own magnetic field. It is believed that the movement of molten iron in Earth's core may be the origin of Earth's magnetic field.

2. 23 marks

   Distinguish cosmic rays from the solar wind, and explain what harm both can cause if unchecked.

   Hint. One kind of particle comes from far across the universe; the other comes from much closer, from our own star.

   ✦ Cosmic rays are tiny, high-energy particles that come from far across the universe, while the solar wind consists of similar particles that come specifically from the Sun. Both can be harmful, since they can damage the atmosphere, reduce the ozone layer, and let in more harmful UV rays that can affect life on Earth.

3. 33 marks

   Explain how Earth's magnetic field protects life, using the chapter's own description.

   Hint. The chapter compares the magnetic field's effect to a specific kind of physical object.

   ✦ 'The Earth's magnetic field acts like a protective shield. It pushes many of these harmful particles away from the Earth, keeping our atmosphere, and hence life on our planet safe.' By deflecting cosmic rays and solar wind particles before they can reach and damage the atmosphere and ozone layer, the magnetic field indirectly protects life from increased UV exposure as well, since blocking the particles upstream prevents the extra ozone damage that would otherwise let more UV through.

4. 43 marks

   Summarise the three factors this chapter says together make Earth a planet where life can emerge and thrive.

   Hint. Position, a specific physical property tied to atmosphere-holding, and a third invisible shield.

   ✦ 'Earth's unique position in the solar system — allows the presence of liquid water — along with its size, atmosphere, and magnetic field, all help make it a planet where life can emerge and thrive.' This is because no single factor alone would be enough — the right distance from the Sun, the right size to hold an atmosphere without crushing life, and a magnetic field shielding against harmful particles all have to work together.

Solutions written by the tuition.in editorial team and checked against NCERT Curiosity — Textbook of Science for Grade 8, Chapter 13 (hecu113.pdf), Reprint 2026-27, pages 210-228. Questions are referenced from the NCERT textbook for identification.