Q. It is said that the sun becomes visible before the actual rise and remains visible even after the actual setting. This makes the day a bit longer. It happens due to:

 2119  205 Ray Optics and Optical Instruments Report Error

Solution:

Refraction of sun rays through the atmospheric air causes bending of the rays. Therefore sun rays reach us even before the sun rises above the horizon. Moreover, the sun rays continue to reach us after the sun goes below the horizon