A doctor need to study chemistry: To know and understand the chemicals processes of matter in the body work which is for example insulin, DNA etc. and to study of all processes in a living organism. The three reasons to study chemistry is because chemistry can be useful in clearing up the natural world, preparing people for career opportunities and producing informed citizens. Some outcomes of modern research in chemistry can lead to technologies that aim to benefit the environment, preserve and produce energy, progress human life and multiply our knowledge of the universe. To help the citizen be a more informed citizen is to let them know how things work makes better decisions and use them better
An image is formed due to reflection of light by a plane mirror. In a completely dark room there is no light so no image will be formed by the mirror placed in the room. Hence we will not be able to see our image in a mirror placed in a completely dark room.
Do you mean penumbra or umbra? Because it is indeed umbra.
The suns gravity causes earth and other planets to revolve around it.
