Sound

Sound of thunder undergoes successive reflections from clouds at different heights and the ground, causing reverberation

Step 1: Reverberation is the persistence of sound due to repeated reflections from multiple surfaces. Step 2: Thunder is produced at one instant by lightning discharge in the atmosphere. Step 3: The sound of thunder reflects repeatedly off clouds at different heights, the ground, and other surfaces. Each reflection returns a slightly delayed version of the sound to our ears. Step 4: This persistence of sound through multiple reflections is called reverberation, which makes the thunder seem to 'roll' and continue. Step 5: Option A is incorrect — the persistence is not due to multiple bolts. Opt

3150 m

Step 1: In SONAR, ultrasound travels from the ship to the seabed and back. So total distance = 2d. Step 2: Total time = 4.2 s; speed = 1500 m/s. Step 3: Total distance = speed × time = 1500 × 4.2 = 6300 m. Step 4: Depth d = 6300 / 2 = 3150 m. Step 5: Option A (6300 m) forgets to divide by 2 — it's the total path, not depth. Option C (1575 m) incorrectly divides by 4. Option D (4200 m) is from a calculation error.

Energy in the form of compressions and rarefactions

Step 1: When a sound source vibrates, it disturbs the particles of the medium near it. Step 2: Each particle oscillates to and fro about its own mean position — it does NOT travel all the way to the listener. Step 3: Each particle only passes the disturbance (energy) to the next adjacent particle, which then passes it further. Step 4: This chain of compressions (high pressure regions) and rarefactions (low pressure regions) moves through the medium, carrying energy from source to listener. Step 5: Option A is wrong — particles stay near their original positions. Option B is wrong for the same

By timbre or quality, because different instruments produce different wave shapes even at the same frequency and loudness

Step 1: Pitch depends on frequency — but both sounds have the same frequency here, so pitch is the same. Step 2: Loudness depends on amplitude — but the problem states both sounds have the same loudness, so amplitude is effectively the same. Step 3: The remaining distinguishing characteristic is Timbre (also called quality). Step 4: Timbre arises because different instruments produce complex waveforms made up of a fundamental frequency and different sets of overtones/harmonics, giving each instrument a unique wave shape. Step 5: This is why a flute and sitar playing the same note at the same v