Physics [1 Mark Question Answer]

The periodic vibrations of body of decreasing amplitude are called the damped vibrations. 

The vibrations of a body with constant amplitude and constant frequency are called free vibrations. 

A stringed instrument is provided with the provision for adjusting the tension of the string. By varying the tension, we can get desired frequency.

No, pitch is not the same as frequency. 

Frequency 512 Hz is twice the natural frequency of the tuning fork (256 Hz), hence the tuning fork will resonate at the frequency 512 Hz. 

The velocity of a wave increases with the increase in temperature. 

The velocity of a wave in a medium depends on the elasticity and density of the medium. 

Wave-velocity = wavelength x frequency 

The amplitude of an oscillation is the height of a crest or the depth of a trough measured from the mean position. The SI unit of amplitude is metre. 

No, transverse waves cannot travel in air. They can only travel in media which posses rigidity. 

Yes, energy is transferred during wave motion. 

Sound waves being mechanical waves need a material medium for their propagation, they cannot travel in vacuum.

Electromagnetic waves have greater speed. 

Sound waves are mechanical in nature. 

Ultrasonic waves are sent in sonar to find the depth of the sea. 

The velocity with which a wave travels in a medium is referred to as wave-velocity.

The process of detecting obstacles by sending ultrasonic waves and hearing the echo is called sound ranging. 

The process of sending ultrasonic waves in all directions to detect obstacles and hearing the echo is called sound signaling. 

Yes, sound waves can be reflected. 

The lowest frequency audible to human ear is 20 Hz and the highest frequency audible to human ear is 20,000 Hz.

A transverse wave propagates by means of crests and troughs.
The high points of the waves are called crests or peaks and the low points of the waves are called troughs.

The sound wave of frequency below 20 Hz is called infrasonic. 

The sound wave of frequency higher than 20,000 Hz are called ultrasonic waves.

The depth of a sea can be found by the process of 'echo depth sounding'. This process is based on the principle of 'echo formation'. 

Full form of RADAR is 'radio detection and ranging'. 

Full form of SONAR is 'sound navigation and ranging'. 

The sound heard after reflection from a rigid obstacle (such as cliff, a hillside, a wall of a building, edge of a forest etc.), is called an echo.

Range of hearing of a normal person is 20 Hz to 20,000 Hz which is called the range of audibility. 

Because the board provides comparatively a large area and forces a large volume of air to vibrate and thereby increases the sound energy reaching our ears.

It is because the vibrations produced by the vocal chord of each person have a characteristic waveform which is different for different persons.

Subjective property of sound related to its frequency is 'pitch'. 

The sound level above 120 dB causes noise pollution. 

Sound of level below 120 dB is safe for our ears. 

Unit used to measure sound level is decibel (dB). 

The audience in the auditorium as act obstructions in the path of sound waves; so they sound waves are not reflected much less and hence the echoes usually decrease.