Chapter 12 light and shadows Part1 Light and

Chapter- 12 light and shadows Part-1

Light and its sources Light is a form of energy that produces sensation of sight in our eyes. Sources of light Natural -Occur naturally e. g Sun, stars, firefly Artificial/ man made -Made by man in factories. e. g Bulb, candles, LED, tubelight etc.

Different types of objects Transparent Objects Translucent Objects Opaque Objects 1. The objects which allow the light to pass through them(almost) completely are called transparent objects. 1. The objects which allow the light to pass through them partially are called translucent objects. 1. The objects which do not allow the light to pass through them (almost) at all are called opaque objects. 2. They do not cast a shadow. 2. They cast a dim shadow. 2. They cast a dark shadow. 3. E. g. Glass, clear water, OHP sheet etc. 3. Plastic scale, butter 3. Cardboard piece, paper, tissue paper, oil wood, metal etc.

Activity-1(To be done in fair notebook)

Shadows Shadow is a dark patch formed on the screen when an opaque object comes in the path of a beam of light. Three essential things for shadow formation are 1. A source of light 2. An opaque object 3. The screen(ground/wall) to obtain the shadow.

Why are shadows formed? The phenomenon of formation of shadow tells us that light , ordinarily, propagates in straight lines. Shadows are formed because light moves along a straight line path, and is not able to bend its path around large obstacles.

DO YOU KNOW?

Watch the video 1. Types of objects, light, path of light https: //www. youtube. com/watch? v=bh. JCO 5 Umr. A&list=PLHOGBLPrsn. Mox 4 La. Hb. MIa. U A 4 fvbl 0 bu 1 z&index=3

Questions to be done in fair notebook -D 1.

Questions to be done in fair notebook D 2. State the type of path that light ordinarily follows when going from one point to another. Ans- Straight line path(Rectilinear propagation). D 3. Do fishes cast shadows in water? Ans- No, because water is a transparent object and does not act as a screen.

Questions to be done in fair notebook E 3. (Answer given in the next slide)

Ans. E 3 Steel glass- Yes, the shadow will be formed because steel glass is an opaque object and it does not allow light to pass through it. Transparent glass- No, the shadow will not form because transparent glass allows the light to pass through it almost completely. READ PAGE NUMBER 188 to 191 OF YOUR BOOK.