Optical Instruments – Astronomical Telescope

Astronomical Telescope Objective lens: Lower powerEye lens: Higher power Position of the object: At infinityNature of the image, I1: Real, inverted and magnified Position of the image, I1: At the principal focus of object lens, fo.Nature of the image, I2: Virtual, inverted and smaller in size. Distance in between the two lens The distance between the object lens and the eye … Read more

Magnifying Glass

Magnifying Glass The magnifying glass is also known as a simple microscope. A magnifying glass is a single convex lens with short focal length. The image formed is virtual, magnified upright A magnifying glass enlarges the image of an object by increasing the virtual angle at the eye when the object is viewed. Angular magnitude … Read more

The Lens Equation

The Lens Equation The following is the lens equation that relates the object distance (u), image distance (v) and the focal length.  When using the lens equation to solve the problem, it’s important to note the positive negative sign of u, v and f. The table below gives the conventional symbol and sign for u, … Read more

Concave Lens

Rules in Drawing Ray Diagram for Concave Lens A light ray passes through the optical centre of the lens will not be refracted. A light ray parallel to the principle axis will be refracted away from the principle focus A light ray moving towards the optical centre will be refracted parallel to the principle axis. … Read more