Practice MCQ Questions and answers on Physics-GK

Glass wool is best used as a sound absorbing material in partition walls. This is so because glass wool do not transfer mechanical energy. These tend to be soft, flexible, low density, and with high surface area to linear area ratios.

Speed of sound is the greatest in glass.

Pitch depends on frequency but also on loudness and spectrum.

Sonar (originally an acronym for Sound Navigation And Ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, communicate with or detect objects on or under the surface of the water, such as other vessels.

Decibel (dB), unit for expressing the ratio between two physical quantities, usually amounts of acoustic or electric power, or for measuring the relative loudness of sounds. One decibel (0.1 bel) equals 10 times the common logarithm of the power ratio.

Sound following a flash of lightning is called Thunder. Thunder or thunder clap always follows lightning because light travels faster than sound. Thunder is caused by the rush of air into the space, created by lightning as it travels from cloud to earth.

Because people can't hear all frequencies, or pitches of sound, A-weighted decibels (dBA) can be used to describe sound based on what human ears can actually hear. Sounds at or below 70 dBA are generally considered safe. Any sound at or above 85 dBA is more likely to damage your hearing over time.

Decibel is a term connected with sound.

Decibel is the unit used for intensity of sound.

The speed of sound in air depends on the type of gas and the temperature of the gas. On Earth, the atmosphere is composed of mostly diatomic nitrogen and oxygen, and the temperature depends on the altitude in a rather complex way.