Practice MCQ Questions and answers on Physics-GK

In transverse waves, particle of the medium vibrate in a direction perpendicular to the direction of wave motion.

Loudness is a subjective characteristic of a sound (as opposed to the sound-pressure level in decibels, which is objective and directly measurable). Perceived loudness of sound is a psycho-acoustic quantity that depends on sound pressure level, the frequency spectrum, and the time behavior of the sound in question. The sone is a unit of perceived loudness that was proposed by Stanley Smith Stevens in 1936.Being a unit of how loud a sound is perceived, the sone scale of loudness is based on data obtained from subjects who were asked to judge the loudness of pure tones and noise. One sone is arbitrarily set equal to the loudness of a 1,000-hertz tone at a sound level of 40 decibels (Encyclopedia Britannica).

The component used for tuning a radio is basically a variable condenser.

A wave with a large amplitude will be particularly tall, and a wave with a small aptitude will be particularly short. It turns out that the amplitude tells you how much energy is in the wave. A high amplitude wave is a high-energy wave, and a low-amplitude wave is a low-energy wave.

In a bounded medium, standing waves occur when a wave with the correct wavelength meets its reflection. The interference of these two waves produces a resultant wave that does not appear to move. Standing waves don't form under just any circumstances.

The wavelength of a wave is the distance between Crest and Crest or Trough and Trough.

Sound waves are longitudinal waves. They cause particles to vibrate parallel to the direction of wave travel. Sound cannot travel through a vacuum because there are no particles to carry the vibrations.

A flight data recorder (FDR) is an electronic device employed to record any instructions sent to any electronic systems on an aircraft. Another kind of flight recorder is the cockpit voice recorder which records conversation in the cockpit, radio communications between the cockpit crew and others (including conversation with air traffic control personnel), as well as ambient sounds. Popularly referred to as a “black box” by the media, the data recorded by the FDR is used for accident investigation as well as for analyzing air safety issues, material degradation and engine performance.

A gradual increase in loudness is known as crescendo.

The wavelength of sound changes with temperature. This is because the speed of sound changes with the temperature. Since the speed of sound is different at different temperature, this means the wavelength of sound at a given frequency is a variable depending on the speed of sound. For example, the wavelength of a 100 cycle tone in air at 68ºF would be 11.27 feet while the same tone in fresh water at 68ºF would have a wavelength of 48.05 feet.