Скачать с ютуб Lenses class 10 | Terminologies of lens | 10th class physics | punjab, federal, kpk, balochistan в хорошем качестве

Lenses class 10 | Terminologies of lens | 10th class physics | punjab, federal, kpk, balochistan

Lenses in urdu hindi and terminologies of lens 12.8 lenses 10th physics wallah chapter 12 ka sabaq. Related searches 1. What are lenses 2. Difference between concave and convex lense 3. Terminology of lenses 12.8 LENSES A lens is any transparent material having two surfaces, of which at least one is curved. Lenses refract light in such a way that an image of the object is formed. Lenses of many different types are used in optical devices such as cameras, eyeglasses, microscopes, telescopes, and projectors. They also enable millions of people to see clearly and read comfortably. Types of Lenses There are different types of lenses. The lens which causes incident parallel rays to converge at a point is known as convex or converging lens. This lens is thick at the centre but thin at the edges (Fig.12.18). Another type of lens causes the parallel rays of light to diverge from a point. This is called concave or diverging lens. This lens is thin at the centre and thick at the edges (Fig.12.19). Lens Terminology Principal Axis: Each of the two surfaces of a spherical lens is a section of a sphere. The line passing through the two centres of curvatures of the lens is called principal axis (Fig. 12.20). Optical Centre, C: A point on the principal axis at the centre of Principal Focus, F: The light rays travelling parallel to the principal axis of a convex lens after refraction meet at a point on the principal axis, called principal focus or focal point F. Hence, convex lens is also called converging lens. For a concave lens, the parallel rays appear to come from a point behind the lens called principal focus F (Fig. 12.21). Hence concave lens is also called diverging lens. Focal Length, f : This is the distance between the optical centre and the principal focus (Fig. 12.21). Fig. 12.21: Concave lens Activity 12.4: Place a convex lens in front of a white screen and adjust its position until a sharp image of a distant object is obtained on the screen. For example, we can do this experiment before an open window to get the image of window on a wall or screen (Fig.12.22). Measure the distance between the lens and the screen. This is the approximate focal length of the lens. Explain. (Hint: Make a ray diagram). What is the nature #lenses #12.8Lenses #differenceBetweenCovexAndConcave #typesOfLenses #10thphysics #sabaq