A class is investigating the reflection of light using a plane mirror, sheet of paper, and optical pins. A student draws a line PQ PQ\,PQ on a ray-trace sheet to mark the position of the plane mirror and draws a normal NM NM\,NM that passes through the centre of PQ PQ\,PQ at point OOO.
(i) The student draws an incident ray line OC OC\,OC of length 9.0 cm starting from point OOO, at an angle of incidence i=40∘i = 40^\circi=40∘ to the normal. The student places a pin P1 P_1\,P1 at point CCC. State the minimum recommended distance from P1 P_1\,P1 at which the student should place a second pin P2 P_2\,P2 on the line OC OC\,OC to ensure an accurate alignment. (ii) State two precautions that should be taken with the pins in this reflection experiment in order to obtain reliable readings.
(i) Under ideal conditions, what is the expected angle of reflection r r\,r between the normal NM NM\,NM and the reflected ray? (ii) When the student extends the lines, they find that the incident and reflected rays do not meet exactly at the point O O\,O on the line PQPQPQ. Suggest a practical reason, related to the equipment, for this observation.
48 exam-style questions on CIE IGCSE Physics 3.2.1a Reflection of light. Each one has a worked solution and a mark scheme showing where the marks go.