CHAPTER-11 LIGHT
NOTES
1. Light travels in a straight line- If light is viewed through a straight pipe, it is clearly visible, but if viewed through a curved pipe, it is not visible.
2. Reflection of light- The change in the direction of light by a mirror is called the reflection of light.
- The image formed by a plane mirror appears upright and is of the same size as the object.
3. South or left- Standing in front of a lane mirror and raising your right (south) hand, the reflection appears as if the left hand is raised.
4. Spherical mirrors- If the reflective surface of a spherical mirror is concave, it is called a concave mirror. If the reflective surface is convex, it is called a convex mirror.
- The inner surface of spoon acts like a concave mirror, while its outer surface acts like a convex mirror.
5. Real image- An image that can be formed on a screen is called a real image.
6. Virtual image- Image that cannot be obtained on a screen are called virtual images.
7. Concave mirror- A mirror with a reflective surface curved inward is called a Concave mirror. The image formed by a concave mirror can be smaller or larger than the object. The image can be real or virtual.
- This mirror is used by dentists to view enlarged images of teeth.
- The reflective surface of torches, car headlights, and scooter headlights is also concave in shape.
8. Convex mirror- A mirror with a reflective surface curved outward is called a Convex mirror. Convex mirrors can form reflections of a larger area. Therefore, they help in viewing a relatively larger area behind vehicles, assisting drivers.
9. Images formed by Lenses- Lenses are transparent. Lenses are widely used in glasses, telescope, and microscopes.
10. Magnifying Lens- It is used to read very small point.
11. Diverging Lens- A concave lens causes incoming light to diverge (bend outward), hence it is called a diverging lens.
12. Converging Lens- A convex lens causes the light falling on it to converge (bend inward), and it is called a converging lens.
13. A convex lens is used as a magnifying lens.
14. The image formed by a concave lens is always virtual, upright, and smaller than the object.
15. Sunlight- Sunlight is a mixture of various colors. It forms a rainbow. The rainbow consists of seven color- red, orange, yellow, green, blue, indigo, and violet. When soap bubbles are formed, they appear colorful. When light is reflected from a CD (compact disc), multiple colors are visible.
- Sunlight consists of seven colors. This type of light is also called white light.
16. Newton’s Disk- When the disk is spun rapidly in daylight, the colors blend together, and the disl appears white. This disk is commonly known as Newton’s Disk.
17. With the help of a prism, white light can be split into many colors.
