The candidates were expected to

(a)(i) Draw five complete traces showing. NO produced to intersect R4R3 produced at T. The normal at O and D
(ii)Measure five values of θ and record in degrees and in trend

Trend: e increases as I increase

(iii)Measure five values of e and record in degrees and in trend Trend: e decreases as it increases
(iv)Show reading on a composite and complete table showing i, θ and e

(v)correctly distinguish the graph axes, select reasonable scales, plot the five points correctly and draw a line that best fits into the points.
(vi)Draw a large right angled triangle on the graph line, read Δe and Δθ and evaluate Δe/Δθ = slope (s)
(vii)Show and read the intercept on the vertical axis;
(viii)Evaluate k = S­¹;
(ix)State any two of the following precautions in the acceptable form of speech:

I ensured neat traces/sharp pencil (shown);
I ensured mirror is firmly attached to prism;.
I ensured pins are reasonable spaced(about 4cm);
I avoided parallax error in reading protractor.

(b)(i)Characteristics of images formed by a plane'
-same size as object
- virtual
- erect
-laterally inverted.
For total internal reflection of light to occur

(ii)- angle of incidence in the denser medium must be greater than the critical angle.
- light must be travelling from a more dense to a less dense medium

This question required candidates to trace the path of light rays through triangular glass prism i.e. air-glass-air media. To measure the angle of emergence e and the angle of deviation from its original path.
Most candidates found it easy to put prisms on paper but found it difficult to trace the rays completely through the glass medium where there occur total internal reflection (the incident angle at the glass/air interface being less than the critical angle of glass); hence, confusion came on.
The short answer question part compared the plane mirror with the glass/air interface and the candidates (a good number of them) were at ease to state the characteristics of a plane mirror producing an image of an object as well as those conditions necessary for total internal reflection to occur.