The correct option is (a).
Explanation
Friction is a resistive force that comes into play when two surfaces are in contact with each other and move or attempt to move relative to one another. It is fundamentally an electromagnetic interaction between the charged particles of the two surfaces.
Statement-wise Analysis:
- Statement 1 is Correct: Friction is a contact force. It arises due to the interlocking of irregularities on the two surfaces in contact. Even surfaces that appear smooth have microscopic irregularities that lock into one another, resisting motion.
- Statement 2 is Incorrect: The force of friction always acts in the opposite direction to the relative motion of the object. If an object is moving to the right, the frictional force acts to the left to oppose that motion.
- Statement 3 is Incorrect: Friction is strictly a contact force because it requires physical contact between surfaces to exist. Non-contact forces (field forces) include gravitational, magnetic, and electrostatic forces, which can act from a distance without physical touching.
Key Takeaway:
Friction is a contact force that always acts opposite to the direction of relative motion between two surfaces.