According to Huygen's principle for the refraction of a plane wavefront,
which of the following equation is correct?
1
when a wave gets refracted into a denser medium (v1 > v2) the wavelength and the speed of propagation decrease but the frequency n (= v/λ) remains the same
2
when a wave gets refracted into a denser medium (v1 > v2) the wavelength and the speed of propagation increase but the frequency n (= v/λ) remains the same
3
when a wave gets refracted into a denser medium (v1 > v2) the frequency and the speed of propagation decrease but the wavelength λ remains the same
4
None of the above