Production of Sound

Sound is produced when an object vibrates. These vibrations create sound waves that travel through the air and reach our ears.

• When objects like the diaphragm of a speaker, a rubber band, or the membrane of a tabla vibrate, they produce sound.
• As long as an object vibrates, sound is produced and can be heard. When the object stops vibrating, the sound also stops.
• The object that vibrates and produces the sound is known as the source of sound. For example, the strings of a guitar or the drumhead of a tabla are sources of sound.

A tuning fork consists of two main parts:

• Prongs: The two U-shaped arms that vibrate when struck.
• Stem: The handle-like part that remains steady while the prongs vibrate.
• The tuning fork vibrates when its prongs are struck, producing sound.

Figure 1:Tuning Fork

Figure 2: Production of sound by tuning fork

1. Stationary Tuning Fork: When the tuning fork is not vibrating, the air around it is in a stable state.

• The air molecules are evenly spaced.
• The air pressure in regions A, B, and C is equal, as shown in Figure 2(a).

2. Vibrating Tuning Fork: When the prongs of the tuning fork are struck, they undergo periodic vibrations (forward and backward motion), and this motion affects the air around them.

Step 1: Compression

When the prongs move away from each other:

They push the surrounding air molecules closer together. This creates a region of high pressure and high density in the air near the prongs (Region A in Figure 2(b)). This region is called a compression.

Step 2: Rarefaction

When the prongs move toward each other:

They create more space for the surrounding air molecules, allowing them to spread out. This creates a region of low pressure and low density near the prongs (Region A in Figure 2(c)). This region is called a rarefaction.

3. Propagation of Sound

The air molecules in this region, which were in a compressed state earlier (Figure 2 (b), region A), transfer their energy to the air molecules in the next region (region B). So, the air in that region becomes compressed (see figure 2 (c), region B). This periodic motion of the prongs creates compression and rarefaction in the air, which propagates away from the prongs. These are nothing but sound waves. When these waves reach our ear, the eardrum vibrates. Accordingly, specific signals reach the brain, and we perceive a sound.

1. Aim: This experiment aims to observe how striking a pot filled with water creates waves and understand the concept of energy transfer through vibration.

2. Requirements: A pot, water, and a spoon or similar object to strike the pot

3. Procedure

• Fill the pot with water, leaving some space at the top to prevent spilling when waves form.
• Place the pot on a stable surface to ensure safety.
• Gently strike the rim of the pot with the spoon. Be sure to strike lightly to observe the effect clearly without spilling water.
• Watch the surface of the water immediately after striking the pot.

4. Conclusion: When the pot is struck, it vibrates. These vibrations are transferred to the water, causing the water to move and create waves. The energy from striking the pot is transferred to the water molecules, which start moving up and down, forming visible waves. This illustrates how energy can be transferred from one object to another and converted into motion.

Vibrations in the water and the production of sound