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NCERT Textbook Questions (Solved)

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              1.   A light ray is incident on a mirror and gets reflected by it (Figure). The angle        i   r
                   made by the incident ray with the normal to the mirror is 40°. What is the
                                                                                                               Mirror
                   angle made by the reflected ray with the mirror?
                   i. 40°          ii. 50°         iii. 45°     iv. 60°
              Ans.  ii.  If the incident ray makes a 40° angle with the normal, then:
                   Angle of incidence (i) = 40°

                   According to the law of reflec on,
                   Angle of reflec on (r) = Angle of incidence (i) = 40°
                   Now, Angle between reflected ray and mirror = 90° – angle of reflec on
                   = 90° – 40° = 50°
              2.   The figure shows three different situa ons where a light
                   ray falls on a mirror:                                                     Incident ray  Incident ray  Normal
                   i.  The light ray falls along the normal.                    Incident ray
                   ii.  The mirror is  lted, but the light ray s ll falls along the   Mirror       Mirror      Mirror
                   normal to the  lted surface.                                    a.            b.           c.
                   iii. The mirror is  lted, and the light ray falls at an angle of 20° from the normal.

                   Draw the reflected ray in each case (Use a ruler and protractor for accurate drawing). What is the angle of
                   reflec on in each case?

              Ans.  Light ray falls along the normal
                     Angle of incidence = 0°
                     Angle of reflec on = 0°
                     The ray retraces its path. It reflects straight back along the same line.
                   ii.  The mirror is  lted, but the light ray s ll falls along the normal to the  lted surface.
                     Even though the mirror is  lted, the ray is s ll perpendicular to the surface.

                     Angle of incidence = 0°
                     Angle of reflec on = 0°
                     The ray again retraces its path — the  lt doesn’t affect the reflec on if the ray is normal to the surface.
                   iii. The mirror is  lted, and the light ray falls at 20° from
                      the normal
                     Angle of incidence = 20°
                     By the law of reflec on:

                     Angle of reflec on = 20°
                     The reflected ray will make a 20° angle with the normal, on the opposite side.
              3.   In the Figure, the cap of a sketch                                           Image  Mirror
                   pen  is  placed  in  front  of  three                                         i.    Plane mirror
                   types  of  mirrors.  Match  each                                              ii.   Convex mirror
                   image with the correct mirror                                                 iii.  Concave mirror


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