Page 1 - Competency Based Worksheet- Light
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SAI INTERNATIONAL SCHOOL

                                                     Class 8

                                   Competency Based Worksheet

                                             Subject- Physics
                                                  Ch. - Light


           For Assertion& Reason question follow the following directions.
           (a) If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
           (b) If both Assertion and Reason are correct, but Reason is not the correct explanation of
           Assertion
           (c) If Assertion is correct but Reason is incorrect
           (d) If Assertion is incorrect but Reason is correct
           (e) If Assertion & Reason both are incorrect
               1.    Assertion: The junction of the optic nerve and retina is called the blind spot.
                    Reason: There are no sensory cells present at the junction of the optic nerve and retina.

               2.    Assertion: Sound travels faster in liquids than in solids.
                    Reason: In solids, the molecules are more closely packed.

               3.    Assertion: Dispersion occurs when light passes through a prism.
                    Reason: Dispersion is the separation of light into its component colours due to different
                    speeds.

               4.    When an object was placed between two plane mirrors inclined at an angle to each
                    other, four images were formed.
                        a)  What is the angle between the two mirrors?
                        b)  Show the relevant formula and calculation.
               5.    After reflection from a smooth plane surface, it was found that the angle between the
                    incident ray and the reflected ray is 150°.
                        a)  What is the angle of incidence?
                        b)  Show the relevant calculation.
                        c)  Calculate the number of images formed if two mirrors are kept at an angle of 30°.

               6.    Explain how the size of the pupil changes in dim light and bright light situations.














               7.    Dispersion of light refers to the phenomenon where light waves are separated into their
                    individual components, each having a different wavelength, as they pass through a
                    medium. This phenomenon is particularly evident when light travels through a prism
                    where we can see that violet colour has bended the most and red has bended the least.
                    When white light passes through a prism, it gets separated into seven colours due to
                    refraction. The colour which has highest wavelength bends the least and the colour
                    having lowest wavelength bends the least. Rainbow is the natural example of dispersion
                    of light. The band of all these seven colours is called spectrum.
                        a)  Which colour has the highest wavelength?
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