Lenses and Refraction of light 03_03_2025.pptx

AQA AS Physics Lenses and Refraction lesson presentation along with annotations

1. Lenses & Refraction (Waves) A-Level Edexcel Physics | Tutoring Lesson Instructor: Muhammad Sameer Sajid Date: 03/03/2025

2. Types of Lenses Convex (Converging) Lens: Bends light inward Application M agnifying glasses C ameras H uman eye correction Concave (Diverging) Lens: Bends light outward Used in glasses for short-sightedness (myopia) Flashlights

3. Refraction Through Lenses Snell’s Law: Light changes direction when passing between materials of different optical densities Convex lenses CONVERGE light rays Concave lenses DIVERGE light rays Applications: Fiber optics Vision correction Camera lenses.  

4. Snell’s Law The image illustrates the phenomenon of light refraction , where a pencil appears bent or displaced when placed in a glass of water. Light travels from water (denser medium, higher refractive index) to air (less dense medium, lower refractive index). This concept is used in optics, corrective lenses, and underwater imaging.

5. Lens e & Magnification Formula Lens formula: f = focal length u = object distance v = image distance Magnification formula: : Image is MAGNIFIED : Image is DIMINISHED  

6. Ray Diagrams for Lenses Convex Lens: Rays CONVERGE to form real or virtual images. Concave Lens: Rays DIVERGE always forming a virtual image. Important for drawing ray diagrams in EXAMS ! CONVEX LENSE CONCAVE LENSE

7. Real-Life Applications of Lenses Glasses & Contact Lenses: Correct vision problems. Cameras & Projectors: Use convex lenses for focusing. Microscopes & Telescopes: Magnify distant or small objects. Magnifying Glasses: Simple convex lens to enlarge objects.

8. Exam-Style Questions (AQA & Edexcel) A convex lens has a focal length of 10 cm. An object is placed 15 cm away. Calculate the image distance and magnification. A concave lens of focal length 20 cm forms an image 5 cm from the lens. Find the object distance and nature of the image. Explain why a concave lens is used for short-sightedness .

9. Solution