A projection lantern is used to give the image of a slide on a screen. If the image is 24 times as large as the slide and the screen is 72.0m from the projecting lens, what is the position of the slide from the lens?
A cell of internal resistance 0.01Ω can be measured accurately using the
What optical instrument can best be constructed with converging lenses of focal lengths 50cm and 5cm?
In a pure semiconductor, the number of electrons in the conduction band is
