Find the locus of a point P whose position vector r satisfies r.a = 0, where a is a constant non-zero vector.

Find the locus of a point P whose position vector r satisfies r.a = 0, where a is a constant non-zero vector.

• A. A sphere
• B. A line
• C. A plane passing through the origin
• D. A cone

Answer: C) A plane passing through the origin

Explanation: The equation r.a = 0 represents all position vectors r that are perpendicular to a constant vector a. This forms a plane passing through the origin, with 'a' as its normal vector.