Ten questions. The result tells you which lessons you may skip.
Model the eye as one lens with the retina \(2.5\,\text{cm}\) behind it. The eye focuses a distant hill and then a book at \(25\,\text{cm}\). Its power changes from
The magnifying power of an instrument is defined as a ratio of angles because
The far point of a myopic eye is \(2\,\text{m}\) away. The correcting lens has a power of
A person cannot see clearly nearer than \(50\,\text{cm}\). To read at \(25\,\text{cm}\), they need
Lines in one direction look sharp and lines at right angles look blurred. The correcting lens is
A simple microscope has \(f = 5\,\text{cm}\). With the image at \(25\,\text{cm}\) and at infinity, its magnifying powers are
In a compound microscope the objective forms an image
A microscope has \(f_o = 1\,\text{cm}\) and \(f_e = 5\,\text{cm}\). The object is \(1.1\,\text{cm}\) from the objective and the final image is at \(25\,\text{cm}\). The magnifying power is
An astronomical telescope has \(f_o = 100\,\text{cm}\) and \(f_e = 5\,\text{cm}\). In normal adjustment its magnifying power and length are
Large astronomical telescopes use mirrors rather than lenses mainly because a mirror