1. LIGHT 1 Creative Commons License Content Sourced and Aggregated by Centre for Positive Learning Supported by TCS iON Learning Exchange  Activity  Assess Knowledge Class VIII / Term II / science

2. A CTIVITY 1 Topic Measurement the angle of incidence and angle of reflection Objective All surfaces which, can reflect light, obey the following two laws, called the laws of reflection. 2 Class VIII / Term II / science

3. A CTIVITY 1 C ONTD … Pre-requisite Knowledge First law of reflection: The angle of incidence(i) is equal to the angle of reflection (r). Second law of reflection: The incident ray, the reflected ray and the normal at the point of incidence all lie in the same plane. The angle of incidence is equal to the angle of reflection. Mathematically, we have  i=  r. Materials required Sheet of white paper, Drawing board, Drawing pins, Plane mirror, Plasticine or Wooden blocks. 3 Class VIII / Term II / science

4. A CTIVITY 1 C ONTD … Steps to perform the activity Take a sheet of white paper and fix it on horizontal drawing board using drawing pins or cellotape. In the middle of the paper, draw a line AB. Place a plane mirror strip exactly along this line. Fix it in position with plasticine or wooden blocks. Draw a line perpendicular to the line AB. This is the incident ray. Place two common pins at any place on this line. See the reflection of the pins in the mirror. Now, on the other side of the normal, place two pins exactly in line with the reflection you see in the mirror. Pull out the pins, and draw a line through these points (pin–points). 4 Class VIII / Term II / science

5. A CTIVITY 1 C ONTD … Demonstration 5 Class VIII / Term II / science

6. A CTIVITY 1 C ONTD … Conclusion You will see that the line draw meets AB at O. Measure the angle of incidence and angle of reflection. The above activity prove that angle of incidence is equal to the angle reflection. 6 Class X / Term II / science

7. A CTIVITY 2 Topic To make a kaleidoscope Objective The principle of forming multiple images by mirrors at an angle to each other is used in a toy called kaleidoscope. It consists of three plane mirror inclined at an angle of 60° to each other. 7 Class VIII / Term II / science

8. A CTIVITY 2 C ONTD … Pre-requisite Knowledge The mirror form multiple images of these glass pieces, resulting in beautiful pattern when seen from the other end. On rotating the cylindrical box, the patterns change continuously as the position of the glass pieces shifts. Materials required Three mirror strips, Piece of cork board, Broken pieces of coloured glass bangles. 8 Class VIII / Term II / science

9. A CTIVITY 2 C ONTD … Steps to perform the activity Firmly tape three mirror strips together so that they are at an angle of 60° to each other, with the shiny surfaces facing inwards. Take a piece of cardboard of the same length as the mirror strips. Bend and fit it around the mirror strips. Tape it in place. Cover the two open ends fo the cardboard with clear plastic and tape it in place. At one end place some broken pieces of coloured glass bangles on the plastic (be careful white handling the bangle piece). Tape some tracing paper on top of the plastic, leaving enough space between the plastic and paper for the bangle pieces to move. 9 Class VIII / Term II / science

10. A CTIVITY 2 C ONTD … Demonstration 10 Class VIII / Term II / science

11. A CTIVITY 2 C ONTD … Observation: Hold your kaleidoscope towards light. Look through the other end and see the beautiful patterns formed as you rotate the tube. Conclusion: The idea of number of images formed by mirrors placed at angle to one another is used in a kaleidoscope to make numerous beautiful patterns. 11 Class X / Term II / science

12. A SSESS K NOWLEDGE CCE Questions (5 Marks) 1. Name the device which uses the principle of multiple images. 2. What is cataract of the eye? 3. State the Laws of Reflection of Light. 4. A smooth shining surface, which rebounds the light back in same or in different direction is called___ 5. Beam of light striking the reflecting surface is called_____ 12 Class X / Term II / science