A wave travels on a light string. The equation of the waves is y=Asin(kx−ωt+30∘) . It is reflected from a heavy string tied to an end of the light string at x=0 . If 64% of the incident energy is reflected, then the equation of the reflected wave is
a. y=0.8Asin(kx−ωt+30∘+180∘)
b. y=0.8Asin(kx+ωt+30∘+180∘)
c. y=0.8Asin(kx−ωt−30∘)
d. y=0.8Asin(kx−ωt+30∘)