Total internal reflection can happen only if the incident beam
originates in the medium with the higher index of refraction and
strikes the interface of the other medium at an angle of incidence
greater than the critical angle.
- D If so = 60 cm and f = 40 cm, the mirror equation tells us that
and, since si is positive, the image is real.
- D Because the image is virtual, we must write the image distance, si, as a
negative quantity: si = −20 cm. Now, with so = 60 cm, the mirror equation
gives
The focal length is half the radius of curvature, so
- C Since the image is projected onto a screen, it must be real, and therefore
inverted. The magnification must be negative, so
