We have two thin concentric conducting spherical shells. There is a charge Q on the inner shell (with radius a) and a charge -Q on the outer shell (with radius b). Find Va-Vb, the difference in potential on the surfaces of the two spheres.

tbh i don't know the answer for this question

answer: the correct answer for the fill in the blank is rods.

rods are the specialized photoreceptor cells that are present in the retina of human eye. they are responsible for vision in the night time ( also called scotopic vision). they have very low visual acuity and color distinguishing ability.

as they are responsible for vision in night time, therefore they are found predominantly in the nocturnal animals.