trên mặt chất lỏng có hai nguồn kết hợp phát ra hai dao động cùng pha u2=u1=Acoswt(cm) s1s2=4 bước sóng. trên đoạn s1s2 có bao nhiêu điểm dao động tổng hợp có biên độ A căn 2

if a star is moving toward earth, its light waves appear to be squeezed together. hope it

a and c

c is 100% but i am confused in a

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.