Q. One issue encountered during the exploration of Mars has been the accumulation of static charge on land-roving vehicles, resulting in a potential of 100 V or more. Calculate how much charge must be placed on the surface of a sphere of radius 0.31 m for the electric potential just above the surface to be 100 V. Assume that the charge is uniformly distributed.
Q. The focal length of a relaxed human eye is approximately 1.52 cm. When we focus our eyes on a close-up object, we can change the refractive power of the eye by about 13 diopters. Calculate the focal length of the eye when we focus closely.