Answer:
reflection, refraction
Explanation:
When the ray of light falls on a highly polished and smooth surface, then after striking it bounce back into the same medium, this phenomenon is called reflection.
So, mirror works on the principle of reflection.
When a ray of light passes from one optical medium to another optical medium, it deviates from its path, this phenomenon is called refraction.
So, lens works on the principle of refraction.
