This question on rotation of mirror was the least popular among the candidates.  It was however satisfactorily answered by the few candidates that attempted it.  The observation was well handled.  The candidates were able to plot the graph of ф against θ, determine slope of the graph and state precautions correctly in acceptable language.  Some candidates however, failed to attach their traces to their answer booklet as demanded in the question.  In part b, few candidates could not state the laws of reflection but were able to list applications of plane mirror.

The expected responses were as follows:

In part (a) the candidates were required to perform the following tasks to score good points

-     Draw five complete traces showing incident ray reflected ray angles ф and θ.
-     Measure and record in degrees five values each of θ and ф in trend. 
      Trend:  As θ increases, ф increases ф = 2θ  2o.
-     Record data in composite table showing θ and ф.
-     Indicate the graph axes, select reasonable scales, plot the five points and line of best fit
      through the points.
-     Determine the slope of the graph using large right-angled triangle
-     State any two of the following precautions in acceptable form of speech.
-     Ensured pins were vertical

-     Avoided parallax error when reading protractor.
-     Evidence of pin spacing
-     Evidence of sharp pencil/neat traces.

The expected responses in part (b) were as follow:

-    angle of incidence (i) = angle of reflection (i)
-    incident ray, reflected  ray and normal (at a point of incidence) all lie in the same
     plane.
       

-    Periscope
-    Looking/dressing mirror/glass
-    Kaleidoscope
-    Sextant.