Waves and Sound MCQ 3

Sound Waves

• Sound is a form of energy that travels through longitudinal mechanical waves.
• It undergoes four wave phenomena: reflection, refraction, diffraction, and interference, but not polarization.
• Interference of sound waves is utilized in noise cancellation technology.

Sound Characteristics

• The loudness of a sound wave depends on its amplitude, with greater amplitude resulting in a louder sound.
• The pitch of a note depends on the frequency of the sound wave, with higher frequency resulting in a higher pitch.

Natural Frequency and Resonance

• Natural frequency is the frequency at which a body oscillates when vibrating freely.
• Resonance is the transfer of energy between two bodies with the same (or similar) natural frequency.

Stationary Waves

• A stationary wave is a wave that remains in a constant position, composed of nodes and antinodes.
• The amplitude of a stationary wave at any point is constant.
• Nodes are points where there is no vibration.
• The distance between a node and the next node is equal to half a wavelength, while the distance between a node and the nearest antinode is 1/4 of the wavelength.

Vibrations and Harmonics

• A string vibrating with an antinode at its center and nodes at each end is vibrating at its fundamental frequency.
• Harmonics are positive integer multiples of the fundamental frequency.
• The quality of a note is dependent on the number and amplitude of harmonics present.

Sound Intensity and Threshold

• The Threshold of hearing (I0) is the smallest sound intensity detectable by the average human ear at a frequency of 1 kHz.
• The Sound Intensity Level (IL) is a scale that compares a particular sound intensity to the threshold of hearing, with a standard unit of decibel (dB).
• Doubling the sound intensity increases the sound intensity level by 3 dB.