OMG ITS B ITS B I HOPE I HELPED U
It's the angle made by the incident ray when it's perpendicular to the surface. (Perpendicular lines are the lines that form a graph or like a 90-degree angle)
Answer:
Part a)

Part b)

Explanation:
Part a)
As we know that the magnetic force on the current carrying wire is given as

so we have


so we have

Part b)
Now magnetic field is changed to 0.55 T
so we will have

