question_answer

An empty test tube dipped into water in a beaker appears silvery, when viewed from a suitable direction. Why?                                               

Answer:

                An empty test tube immersed in water appears silvery white when viewed from the top. It may happen that for the light rays passing from water (denser medium) to air inside the tube (rarer medium), the angle of incidence is greater than the critical angle. Such light rays will suffer total internal reflection. Due to this, the tube will give silvery appearance.