Ultrasonic waves, propagating through a medium, can be detected by:
Piezoelectric detector: This method uses a piezoelectric crystal that generates an electrical charge when subjected to mechanical vibrations, which are caused by ultrasonic waves. The charge can then be measured to detect the presence of the ultrasonic wave.
Y and Z are two partially reflecting glass sheets, a distance apart in air. White light falls normally on Y. The light emerging from Z is analysed by a spectrometer. A dark band is observed in the spectrometer at a wavelength. The distance must be equal to:
A tuning fork, vibrating with a frequency of 90 Hz. is moving towards an observer with a with a speed of 0.1 times the speed of sound. The frequency of the note heard by the observer would be:
Superposition of two waves trains of same amplitudes and nearly same frequencies, moving in the same direction, results in the formation of beats. The maximum loudness heard at the waxing is n times the loudness of each of the component wave trains. The value of n is:
The Poynting vector of electromagnetic waves has the same dimensions as that of:
