Waves

If a wave gets refracted into a denser medium, then which of the following is true?

A person observes two moving trains, 'A' reaching the station and 'B' leaving the station with equal speed of $$30 \mathrm{~m} / \mathrm{s}$$. If both trains emit sounds with frequency $$300 \mathrm{~Hz}$$, (Speed of sound: $$330 \mathrm{~m} / \mathrm{s}$$) approximate difference of frequencies heard by the person will be:

For a transverse wave travelling along a straight line, the distance between two peaks (crests) is 5 m, while the distance between one crest and one trough is 1.5 m. The possible wavelengths (in m) of the are :

Tube $$A$$ has bolt ends open while tube $$B$$ has one end closed, otherwise they are identical. The ratio of fundamental frequency of tube $$A$$ and $$B$$ is

length of a string tied to two rigid supports is $$40$$ $$cm$$. Maximum length (wavelength in $$cm$$) of a stationary wave produced on it is

When temperature increases, the frequency of a tuning fork

The displacement $$y$$ of a wave travelling in the $$x$$-direction is given by $y = {10^{ - 4}}\,\sin \left( {600t - 2x + {\pi \over 3}} \right)\,\,metres$ where $$x$$ is expressed in metres and $$t$$ in seconds. The speed of the wave - motion, in $$m{s^{ - 1}}$$, is

The displacement $$y$$ of a particle in a medium can be expressed as, $$y = {10^{ - 6}}\,\sin$$ $$\left( {100t + 20x + {\pi \over 4}} \right)$$ $$m$$ where $$t$$ is in second and $$x$$ in meter. The speed of the wave is

A sound absorber attenuates the sound level by $$20$$ $$dB$$. The intensity decreases by a factor of

Which of the following equations represents a travelling wave?