Upon exiting the water, the light bends outward at the same angle when it enters the water. In this version, the conjunction is ‘when’ . You may rewrite the sentence thus: Upon exiting the water, the angle at which the light bends outward is the same as it enters the water.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
Yes. That's fine, too.
What about this?
Upon exiting the water, the light bends outward at the same angle at which it bends upon entering the water.