Answer: C and D
Explanation: One of the first rule for total internal reflection to occur is that the ray must move from a dense to a less dense medium, hence refractive index of medium a must be greater than that of b.
When a ray moves from a dense to a less dense medium, the refracted ray moves away from the normal thus increasing the size of the angle of refraction (total internal refraction occurs when the angle of refraction is 90° and the angle of incidence at this point is known as the critical angle), hence the angle of incidence must be greater than the critical angle.
These points verifies option C and D
Answer:
all of above I think sorry if I'm not right but I tried
Answer: a) speed = 3.45 × 10^-2 m/s
b) speed = 1.38 × 10^-1 m/s
Explanation: shown in the attachment
Answer: 
Explanation:
The angular diameter 
of a spherical object is given by the following formula:
Where:
is the actual diameter
is the distance to the spherical object
Hence:
This is the angular diameter
The equation for this is very simple you add then you subtract then you get the answer then you divide then it all works out for you
