Mention three practical applications of curved mirror. In two lines define Echo? State four application of echo? State three characteristics of sound waves and it's dependent.

Here are three characteristics of sound waves and their dependencies:

• Loudness (Intensity): This characteristic depends on the amplitude of the sound wave. A larger amplitude corresponds to a louder sound.
• Pitch: This characteristic depends on the frequency of the sound wave. Higher frequency waves produce higher-pitched sounds, while lower frequency waves produce lower-pitched sounds.
• Quality (Timbre): This characteristic depends on the waveform of the sound, which is determined by the presence and relative intensity of different harmonics or overtones. It allows us to distinguish between different instruments or voices even if they are playing the same note at the same loudness.