ce Phy mc 3題

18. The answer is B.

By n1/n2 = v1/v2

1/n2 = 340/1500

Acoustic refractive index of air relative to sea, n2 = 4.41

The angle of incidence = 50*

By Snell's law,

n1sini = n2sinr

(1)sin50* = 4.41sinr

Refracting angle, r = 10*


20. The answer is B.

Options A and D are not relative to the question.

Option C. It should be UV light has a small diffraction when it passes through the skin, this allows the detection to be more precise.

Option B, UV light has a high penetrating power, so that it can go inside the human skin easily.


30. The answer is D. This is the AL 03 physics mc Q.1, this item has been deleted since it is wrong.

So, just ignore this one.