2. A 2.5 meter-long wave travels at 1 m/s towards a fixed boundary. After 2 seconds, how does the wave appear?

Since incident wave and its reflected part in opposite phase superimpose on each other

So correct answer will be

Option B

Explanation:

Here we know that the wave reflection is done by rigid boundary

So when wave is reflected by the boundary then its phase is reversed by 180 degree

so the reflected wave is in reverse phase from the boundary

so we can superimpose the reflected part with incident wave to dine the resultant wave

So the phenomenon is given as follow

absorption lines are where light has been absorbed by the atom thus you see a dip in the spectrum whereas.

emission spectra have spikes in the spectra due to atoms releasing photons at those wavelengths.

explanation:

an obstruction