SHARMA CLASSES BHARATPUR

  SHARMA CLASSES BHARATPUR Class 10 numerical on mirrors 1.     A 5 cm tall object is placed perpendicular to the principal axis of a convex lens of focal- length 20 cm. The distance of the object from the lens is 30 cm. Find the: (i) position (ii) nature (iii)  size of the image formed. 2.     4.5 cm needle is placed 12 cm away from a convex mirror of focal length 15 cm. Give the location of image and magnification. Describe what happens to the image as the needle is moved farther from the mirror. 3.     Rohit placed a pencil perpendicular to principal axis in front of a converging mirror of focal length 30 cm. The image formed is twice the size of the pencil. Calculate the distance of the object from the mirror. 4.     An object is placed at a distance of 25 cm away from a converging mirror of focal length 20 cm. Discus the effect on the nature and position of the image if the position of the object changes from 25 cm to 15 cm. Justify your answer without using mirror fo

  PHYSICS WORKSHEET REFRACTIVE INDEX 1. The refractive index of medium ‘X’ with respect to medium ‘Y’ is 2/3 and refractive index of medium ‘Y’ with respect to medium ‘Z’ is 4/3. Find the refractive index of medium ‘Z’ with respect to medium ‘X’. 2. The refractive index of water with respect to air is 4/3. What is the refractive index of air with respect to water? 3. The refractive index of glass with respect to air is 1.65 and that of water w.r.t air is 1.33. Calculate refractive index of water w.r.t to glass.   4. In an experiment with a glass slab, a student observed that a ray of light incident at an angle of 60 ͦ with the normal on one face of the slab, after refraction, strikes the opposite face of the slab before emerging out in air making an angle of 42 ͦ with the normal. Draw a labelled diagram to show the path of this ray. What would be the value of angle of refraction and angle of emergence? 5. Refractive index of water and benzene w.r.t air are 1.33 and 1.50 respect

  Synthetic Fibres And Plastics   Fabrics are made of fibres which are obtained from natural and artificial sources. Wool, silk, and cotton are a few examples of natural fibres and fibres like polyesters and terylene are a few examples of synthetic fibres. Natural Fibre The naturally occurring fibres that humans derive from plants or animals are known as natural fibres. Eg: cotton, wool, silk, etc. ·          Basic component of animal fibres is Protein Synthetic Fibre Fibres that are made or created by humans are known as synthetic or man-made fibres. Humans have been able to make a variety of synthetic fibres. Eg: rayon, nylon etc. Synthetic fibres may be synthesised by two ways: ·          By regenerating them from natural fibres, like in rayon. ·          By using entirely chemicals and chemical reactions, like in nylon. Synthetic fibres have many advantages as compared to natural fibres. Some of them are as follows: They are very stron