(A): In solids mechanical waves can be either transverse or longitudinal depending on mode of excitation.
(B) : Waves on strings are always transverse.

Options

A. Both A and B are true
B. Both A and B are false
C. A is true, B is false
D. A is false, B is true

Answer

To analyze the given statements A and B, let's break down the concepts involved step by step.

### Step 1: Understanding Statement A
- **Statement A**: "In solids, mechanical waves can either be transverse or longitudinal depending on the mode of excitation."
- **Explanation**: Mechanical waves in solids can indeed be either transverse or longitudinal. This classification depends on how the medium is set into vibration:
- **Transverse Waves**: These occur when the vibrations are perpendicular to the direction of wave propagation. For example, if you shake a rope up and down, the wave travels along the length of the rope while the particles of the rope move up and down.
- **Longitudinal Waves**: These occur when the vibrations are parallel to the direction of wave propagation. An example is a sound wave traveling through air, where air molecules compress and rarefy in the same direction as the wave travels.
- **Conclusion for Statement A**: This statement is **True**.

### Step 2: Understanding Statement B
- **Statement B**: "Waves on strings are always transverse."
- **Explanation**: While it is true that waves on strings are typically transverse (as seen when you pluck a guitar string), this statement is misleading. It suggests that all types of waves on strings must be transverse, which is not accurate. For instance, if you consider a string under tension, it primarily supports transverse waves. However, if the string is not under tension or if it is subjected to longitudinal vibrations (for example, in certain experimental setups), it can also support longitudinal waves.
- **Conclusion for Statement B**: This statement is **False**.

### Final Conclusion
- **Statement A**: True
- **Statement B**: False

### Summary of Answers
- Statement A is True.
- Statement B is False.