Question

If light source is at focus of concave lens, then after refraction the ray of light will ____________.

• A. parallel to the principal axis
• B. will appear to be parallel to the principal axis
• C. will never be parallel to the principal axis
• D. cannot be determined

Answer 1

The correct option is C

will never be parallel to the principal axis

By drawing normal at both the curved surfaces and following Snell's law, we see the rays are becoming even more divergent and not parallel. Thus, if the light source is the focus of the concave lens, then after refraction the ray of light will never be parallel to the principal axis.