Which of the following is the primary cause of mechanical waves?

• A. The spontaneous emission of energy in a vacuum
• B. The oscillation of electromagnetic fields without a medium
• C. The movement of charged particles in an electric field
• D. A disturbance that propagates through a medium due to particle interactions

Answer: (D)

Verified step by step guidance

1. Understand that mechanical waves require a medium (such as air, water, or a solid) to travel through because they rely on the interaction between particles in that medium.
2. Recognize that mechanical waves are generated by a disturbance or vibration that causes particles in the medium to oscillate around their equilibrium positions.
3. Note that this oscillation of particles transfers energy from one particle to the next, allowing the wave to propagate through the medium.
4. Distinguish mechanical waves from electromagnetic waves, which do not require a medium and are caused by oscillating electric and magnetic fields.
5. Conclude that the primary cause of mechanical waves is a disturbance that propagates through a medium due to particle interactions, not spontaneous emission or electromagnetic field oscillations.