Understanding Light, Lenses, and Mirrors: Final Exam Review

[dranseth]

Homework Statement

I have a final tomorrow, and I there are a couple questions that I don't know.

When the angle of incidence is the critical angle, the angle of refraction will be?

If a screen is moved 3 times the distance from a light source, what will the intensity on the screen be reduced to?

A ray of light is incident at 38º on a curved mirror. At what angle will the reflected ray leave the mirror?

Homework Equations

n1sin90º=n2sin(critical angle)
I'm not sure which formula to use for the one regarding light intensity, and for the last, I drew it out.

 

[Leong]

90 degree [according to the definition of critical incident angle]

2. don't know

3. 38 degree [ according to the laws of reflection of light: the reflected angle is equal to the incident angle]