**Q3: **

The diagram shows a plane wave that is incident on a reflective surface. The wave propagates
as described by the Huygens wave model. The points A, B, C, and D are point sources of
wavelets emitted from the reflective surface.

How many wavelengths of the plane wave does the wave front of the wavelet that originates
at point D travel to reach point H?

How many wavelengths of the plane wave does the wave front of the wavelet that originates
at point B travel to reach point F?

The number of wavelengths of the plane wave that are traveled by the wave front of the
wavelet that originates at point A to reach point E is . The number of
wavelengths of the plane wave that are traveled by the wave front of the wavelet that
originates at point C to reach point G is . What is the ratio of
to ?