Assertion (A) : Two magnetic field lines around a current carrying straight wire do not intersect each other. Reason (R) : The magnitude of the magnetic field produced at a given point increases as the current through the wire increases.
Assertion (A) : Two magnetic field lines around a current carrying straight wire do not intersect each other. Reason (R) : The magnitude of the magnetic field produced at a given point increases as the current through the wire increases.
Options
b
Marking Scheme
- 11 mark for correctly identifying that both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
Hint
Check if both statements are individually correct. Then ask yourself: Does the fact that the magnetic field increases with current explain why two field lines cannot cross?
Quick Oral Answer
Two magnetic field lines never intersect because if they did, a magnetic compass placed at the point of intersection would have to point in two different directions at the same time, which is physically impossible.
Analysis & Explanation
- Assertion (A) is true: According to the NCERT text, 'No two field-lines are found to cross each other. If they did, it would mean that at the point of intersection, the compass needle would point towards two directions, which is not possible.' This is a fundamental property of all magnetic field lines, including those around a current-carrying straight wire.
- Reason (R) is true: According to the NCERT text, 'if the current is increased, the deflection also increases. It indicates that the magnitude of the magnetic field produced at a given point increases as the current through the wire increases.' Thus, the statement in the Reason is factually correct.
- Relationship: Although both Assertion (A) and Reason (R) are true, the Reason (which describes how the magnetic field strength scales with current) does not explain why magnetic field lines do not intersect (which is due to the uniqueness of the magnetic field direction at any given point).
Therefore, both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A). This corresponds to option (b).
Common Mistakes
- 1Students often assume that if both statements are scientifically true, then the Reason must automatically be the correct explanation. Always verify if there is a cause-and-effect relationship between them.
Interesting Facts
The non-intersection of magnetic field lines is a direct consequence of the vector nature of the magnetic field, which can only point in one unique direction at any single point in space.
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Frequently Asked Questions
How many marks does this question carry in CBSE Class 10 Science 2023?
This question carries 1 mark in the CBSE Class 10 Science 2023 examination.
Which chapter does this question come from in Science?
This question is from the chapter "Magnetic Effects of Electric Current" in the CBSE Class 10 Science syllabus.
What topic does this question cover in Science?
This question covers the topic "Properties of Magnetic Field Lines" from CBSE Class 10 Science.
What type of question is this in the CBSE Class 10 Science 2023 paper?
This is a MCQ question from Section A in the CBSE Class 10 Science 2023 paper.