Geometrical Optics

• Very Important Multiple Choice Questions (MCQs) with Answers of Chapter No.10: Geometrical Optics in Physics Class 11 Sindh Book Boards.
• Definition of Geometrical Optics
• Describe Converging Or Convex Lenses
• Describe Diverging Or Concave Lenses
• Principal Focus Or the Focal Point
• Definition of Focal Length
• Properties of Rays
• Describe Thin Lens Formula
• Describe Combination of Lenses
• Describe Angular Magnification
• State and Explain Compound Microscope with its Construction, Angular Magnification.
• Construct and describe Astronomical Telescope
• State and Explain Galilean Telescope 
• Defects In Lenses Or Lens Aberration: 1. Spherical Aberration 2. Chromatic Aberration
• Explain Chromatic Aberration
• An object 4 cm tall is placed near the axis of a thin converging lens. If the focal length of the lens is 25 cm, where will the image be formed and what will be the size of the image? Sketch the principal ray diagram
• A convex lens has a focal length of 10 cm. Determine the image distances when an object is placed at the following distances from the lens. 50 cm, 20 cm, 15 cm, 10 cm and 5 cm.
• Two converging lenses of focal lengths 40 cm and 50 cm are placed in contact. What is the focal length of this lens combination? What is the power of the combination in diopters?
•  A converging lens of focal length 20 cm is placed in front of a converging lens of focal length 4 cm. What is the distance between the lenses if parallel rays entering the first lens leave the second lens as parallel rays?
• A parallel light beam is diverged by a concave lens of focal length -12.5 cm and then made parallel once more by a convex lens of focal length 50 cm. How far are the two lenses apart.
• Two lenses are in contact, a converging one of focal length 30 cm and a diverging one of focal length - 10cm. What is the focal length and power of the combination?
• Moon light passes through a converging lens of focal length 19 cm, which is 20.5 cm from a second converging lens of focal length 2 cm. Where is the image of the moon produced by the lens combination?
• Find the distance at which an object should be placed in front of a convex lens of focal length 10 cm to obtain an image of double its size?
• A compound microscope has a 12 mm focal length objective and a 75 mm focal length eye piece, and the two lenses are mounted 200 mm apart. If the final image is 225 mm from the eye piece, what is the magnification produced?
• An astronomical telescope of angular magnification 1000 has an objective of 15 m focal length. What is the focal length of the eye piece?
• A Galilean telescope has an objective of 120 mm focal length and an eye piece of 50 mm focal length. If the image seen by the eye is 300 mm from the eye piece, what is angular magnification?
• A compound microscope has an objective with a focal length of 10 mm and a tube 100 mm long. An image is produced 250 mm from the eye piece when the object is 12 mm from the objective. What is the angular magnification?
• A converging lens of 4 dioptres is combined with a diverging lens of -2 dioptres. Find the power and focal length of the combination?
• A convex lens forms image of an object on a fixed screen 20 cm from the lens. On moving the lens 60 cm towards the object, the image is again formed on the screen. What is the focal length of the lens?
• Two converging lenses are 25 cm part. Focal length of each is 10 cm. An object is placed in front of one lens at 50 cm. Find the distance between the object and the final image?
• Two converging lenses of focal length 40 cm and 50 cm are placed in contact. What is the focal length of this tens combination? 
• An astronomical telescope with small amplitude has an objective whose power is 2 diopters. The lens is placed 60cm from the eye piece, when the telescope is adjusted for minimum eye strain. Calculate the angular magnification of the telescope. 
• An astronomical telescope having angular magnification 5 consists of two thin lenses 24 cm apart. Find the power of its lenses.
• An astronomical telescope has a length of 105 cm and its magnification is 6. Determine the power of objective and eye piece?
• A microscope has an objective of 12mm focal length and eye piece of 25 mm focal length. What is the distance between the lenses? What is the magnifying power if the object is in sharp focus when it is 15 mm from the objective?
• A lens 2 cm focal length is to be used as a magnifying glass. How far from the lens should the object be placed? What is its magnifying power?
• A watch maker uses a magnifying glass of local length 5cm to see the damaged spring of a watch. If he holds the glass close to the eye what is the best position of the object? What is the linear magnification?
• A magnifying glass of focal length 6 cm is used to see a small specimen. The least distance of distinct vision of the observer is 25 cm. What is the magnifying power of the lens?
• Two converging lenses of focal lengths 30 cm and 60 cm are placed in contact. What is the focal length of this combination? Calculate the power of the combination in dioptres.
• A magnifying glass produces an image of magnifying 6. What is the power of the lens? What is the best position of the object if a watch maker holds the same lens close to his eye to see the damaged spring of the watch?