LIGHT - 2 | SPEED NOTES | SCIENCE | CBSE | CLASS 7

Chapter – 15 Light Light: It is the natural agent that stimulates sight and makesthings visible. Light travels along straight line. Any polished ora shining surface acts as a mirror. An image which can be obtained on a screen is called areal image. It isformed by light rays that actually pass through thescreen. An image which cannot beobtained on ascreen is called a virtual image. It isformed by lightrays that seemto pass through the screen. The image formed by aplane mirror iserect. It isvirtual and isof the samesize as theobject. The image isat the samedistance behind themirror as theobject is infront of it. In an image formed by amirror, the leftside of theobject is seenon the right side in theimage, and right side of theobject appears to be onthe left sidein the image. A concave mirror can forma real andinverted image. Whenthe object isplaced very close to the mirror, the image formed is virtual, erectand magnified. A Convexmirror is themirror that curves out; the reflecting surface is convex. Image formed is virtual, upright and diminished. Image formed by a convex mirror is erect, virtual and smaller insize than theobject. A Concave lens is thelens that isthinner at thecenter than atthe edges. Itis a diverging lens. Image formed is virtual, erect and diminished. A convexlens can formreal and inverted image. When theobject is placed very close to the lens, the imageformed is virtual, erectand magnified. When used to see objects magnified, the convex lens is called a magnifying glass. White light is composed ofseven colors. Properties ofLight: 1. Rectilinear Propagation of Light: It is the property of light by which it travels in a straight linein any direction. The direction ofpath in whichlight make a ray.

2. Reflection of Light: It is the bouncing back of lightafter striking thesurface of an object. Shiny smooth surfaces reflect almost all the light. 3. Dispersion: It is thephenomenon of splitting of white lightinto its seven colors. White light is mixture of:Violet, Indigo, Blue, Green, Yellow, Orange and Red (VIBGYOR) colors.