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A: The earth's field departs from its di...

A: The earth's field departs from its dipole shape substantially at large distances (greater than about 30,000 km).
R: At large distances, the field gets modified due to the field of ions in motion in the ionosphere which is sensitive to extra-terrestrial distubances such as, the solar wind.

A

If both Assertion & Reason are the true and the reason is the correct explanation of the assertion, then mark (1)

B

If both Assertion & Reason are true but the reson is not the correct explanation of the assertion, then mark (2)

C

If Assertion is true statement but Reason is false, then mark (3)

D

If both Assertion and Reason are false statements, then mark (4)

Text Solution

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The correct Answer is:
To determine the correctness of the assertion (A) and reason (R) provided in the question, we can analyze them step by step. ### Step 1: Understand the Assertion (A) The assertion states that "The earth's field departs from its dipole shape substantially at large distances (greater than about 30,000 km)." - **Analysis**: The Earth's magnetic field can be approximated as a dipole field close to the surface. However, as we move further away from the Earth, particularly beyond 30,000 km, the influence of the Earth's magnetic field changes due to various factors. ### Step 2: Understand the Reason (R) The reason states that "At large distances, the field gets modified due to the field of ions in motion in the ionosphere which is sensitive to extra-terrestrial disturbances such as the solar wind." - **Analysis**: The ionosphere is a region of the Earth's atmosphere that contains a high concentration of ions and free electrons. The motion of these ions can create additional magnetic fields. Moreover, the solar wind, which consists of charged particles emitted by the sun, can interact with the Earth's magnetic field and the ionosphere, leading to distortions in the magnetic field. ### Step 3: Correlate Assertion and Reason Now we need to see if the reason provided supports the assertion. - The assertion is about the change in the Earth's magnetic field at large distances, while the reason explains how the motion of ions and external disturbances (like solar wind) contribute to this change. ### Step 4: Conclusion Both the assertion and the reason are correct and are related. The Earth's magnetic field does indeed depart from its dipole shape at large distances due to the influence of the ionosphere and external factors like solar wind. ### Final Answer Both assertion (A) and reason (R) are correct, and the reason supports the assertion. ---
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AAKASH INSTITUTE ENGLISH-MAGNETISM AND MATTER -ASSIGNMENT (SECTION D)
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  5. A: The earth's field departs from its dipole shape substantially at la...

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  11. A: Peramability of a ferromagnetic material is independent of the magn...

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  16. A: Diamagnetism is exhibited by all the substances. R: Diamagentism ...

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