User: The greenhouse effect is a result of A. absorption and radiation of energy in the hydrosphere. B. consumption of fruits and vegetables that produce a biofuel. C. absorption and radiation of energy in the atmosphere.
A principal focus or focal point is a special focus: 1  For a lens, or a spherical or parabolic mirror, it is a point onto which collimated light parallel to the axis is focused. Since light can pass through a lens in either direction, a lens has two focal pointsâone on each side.
focal point noun (INTEREST) âº [ C usually singular ] the thing that everyone looks at or is interested in: The fireplace is usually the focal point of the living room. focal point noun (SCIENCE) focal point in American English. focal pointnoun [ C ] âº art A focal point is the feature of a work of art that is the most interesting or important or the most strongly emphasized.