"Magnetic field is a physical quantity that has both direction and magnitude." How can this statement be proved with the help of magnetic field lines of a bar magnet ?
Generated by claude-sonnet-4-6 · 2026-06-15 06:51 · grounding rag
Model Answer
Magnetic field lines of a bar magnet prove this as follows:
- Direction: By convention, field lines emerge from the north pole and merge at the south pole (outside the magnet), and run from south to north inside it. The direction of the field at any point is the direction a free north pole would move there.
- Magnitude: Where field lines are crowded (near the poles), the field is stronger; where they are spread apart, the field is weaker.
Since field lines show both direction and magnitude, magnetic field is proved to be a vector quantity.
Source: Chapter 12, Section 12.1 — Magnetic Field and Field Lines
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Explanation
Examiners expect two distinct points: one linking field-line direction to the direction of the field, and one linking crowding/spacing of field lines to the magnitude/strength. Mentioning "vector quantity" as the conclusion is a bonus but keeps the answer crisp. Avoid lengthy descriptions of the bar-magnet diagram; just state the two properties directly.