a) global temperature become lower
b) the earth warms up due to CFCs is a greenhouse gas
c) CFCs lead to ozone depletion and hence more ultraviolet rays come in so it is warmer CFCs is also a greenhouse gas
An object pin is placed 20cm in front of a convex lens which is 10 cm away from a plane mirror . An inverted image is found at the same position of the object(above the object).
What is the focal length?