b = light
1
2
b
b
y
x
1 cannot be seen but 2 can be seen. 1 cannot be seen because of the light can pass through objek X but light cannot pass through object y so 2 can be seen.
a) b
b
f
/
x
a) b ( light ) go over object f : b go over f so object f remains as f. - Depends on the type of materials. b) b ( light ) pass through X and come out from object X and remains b ( light ) : b pass through X and become b again so object X may become X2 or X-2. - Speed of light decreased - so the object may be bigger or smaller.