Acoustics and Sound Waves

Meow 104.8 FM is an Indian radio station that broadcasts at 104.8 MHz, primarily in the Delhi region. The station's name directly references its frequency, making it easy to remember. The other options include frequencies for Fever FM (104.0) and FM Rainbow (102.6).

Sound travels approximately 1,500 meters per second in water compared to about 340 meters per second in air. The ratio is roughly 4.4:1, so '4 times faster' is the closest approximation among the options. This difference occurs because water is denser and less compressible than air, allowing sound waves to propagate more efficiently.

The pain threshold for human hearing is around 120-130 dB, which causes discomfort or pain in the ear. Normal conversation is 60-70 dB. Prolonged exposure above 85 dB can damage hearing. The "dba" appears to be a typo for "dB" but the numerical range is correct.

Sound is produced by the vibration of air molecules or any medium. These vibrations create pressure waves that our ears detect as sound. 'Photons of sound' is incorrect - photons are particles of light, not sound. Loudness is measured in decibels, not bels, making option C inaccurate.

Wavelength is defined as the distance between two consecutive crests or troughs of a wave. It represents the spatial period of the wave. Loudness is related to amplitude, frequency is the number of wave cycles per second, and amplitude is the maximum displacement from equilibrium.

Frequency is measured in both hertz and cycles per second - these are equivalent units. One hertz equals one cycle per second. This is a case where both naming conventions are valid and used interchangeably in physics.

Normal conversation typically measures around 60 decibels. 100 dB would be extremely loud (like a chainsaw or motorcycle), 50 dB is quieter than normal speech, and 80 dB is closer to heavy traffic or a noisy restaurant. The 60 dB range accurately represents typical human conversation levels.

Sounds with frequencies higher than 20,000 hertz are called ultrasonic. This is above the upper limit of human hearing. Infrasonic refers to sounds below 20 Hz, supersonic refers to objects moving faster than the speed of sound, and sonic boom is the shockwave created when an object breaks the sound barrier.

At sea level and 25°C, the speed of sound in air is approximately 346 meters per second. Among the given choices, 330 m/s is the closest standard approximation often used in physics problems for air at slightly cooler temperatures (0-20°C).

Sound actually travels FASTER in humid air because water vapor is less dense than dry air (the molecular weight of H₂O is 18 vs N₂=28, O₂=32). Lower density means faster sound propagation, making statement C the incorrect one.

Supersonic refers to speeds faster than the speed of sound (Mach 1, about 1235 km/h). 'Super' means above or beyond, so supersonic means beyond sound speed. Light speed is much faster, gravity is a force not a speed, and warp speed is science fiction.

Echolocation is a biological system where animals emit sound waves and interpret the echoes to navigate and find objects. Bats and dolphins are famous users of echolocation. Doppler effect describes frequency change, ultrasound is high-frequency sound used in imaging, and echomilekko is not a real term.

The loudest sound produced by any animal is NOT from the African Elephant. The sperm whale produces clicks that can reach 230 decibels. Even among terrestrial animals, the howler monkey or certain other species produce louder sounds than elephants. The claim is false.

Dog whistles produce ultrasonic sounds (above 20 kHz) which are beyond the range of human hearing but within dogs' hearing range. Dogs can hear frequencies up to about 45-65 kHz, much higher than humans. Infrasound (below 20 Hz) would not be useful for dog training as dogs also have limited sensitivity there.