S2 Science: Reflection, Refraction And Dispersion Of Light (Paper 4 (error Clinic))

S2 Science: Reflection, Refraction and Dispersion of Light (Paper 4 (error clinic))

2026-11-14

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Tutor Prep Guide · The law of reflection and plane mirror images, judging refraction direction, prism dispersion and total internal reflection

S2 Science: Reflection, Refraction and Dispersion of Light (Paper 4 (error clinic))

This paper reworks the most common wrong answers, including measuring from the mirror, refraction direction, the direction of total internal reflection and virtual images.

Direct answers　The point of error clinic practice is to find whether the fault was the reference line, the direction of the media or the use of the formula.

01　Paper details (check answers afterwards)

Item	Detail
Questions	10
Suggested time	20
Difficulty mix	Foundation 3 · Intermediate 3 · Challenge 3 · Error redo 1
Chapter	Chapter: S2 Science: Reflection, Refraction and Dispersion of Light
Level	S2

02　Questions (10 items)

FoundationWith an angle of incidence of 30 degrees the ray makes 60 degrees with the mirror surface. Is 60 degrees the angle of reflection?
FoundationLight goes from air into glass with an angle of incidence of 35 degrees and an angle of refraction of 20 degrees. Does it bend towards or away from the normal?
FoundationAfter passing through a prism, which bends more, violet or red?
IntermediateA ray strikes a plane mirror along the normal. What is the angle of reflection and where does the ray go?
IntermediateA plane mirror turns through 10 degrees. How far does the reflected ray turn?
IntermediateLight goes from glass into air with an angle of incidence of 35 degrees and an angle of refraction of 60 degrees. Which way does it bend?
ChallengeWater has a critical angle of about 48.8 degrees. Does light at 45 degrees going from water into air reflect totally?
ChallengeWhat is the speed of light in glass of refractive index 1.5?
ChallengeAfter a prism separates white light, a second identical prism is placed the other way round. What happens?
Error redoA student says the image in a plane mirror is real and can be caught on a screen. What is wrong?

03　Answers and one-line notes

#	Answer	One-line note
1	No, the angle of reflection is 30 degrees	Angles are measured from the normal, so 60 degrees is only the angle with the surface.
2	Towards the normal	Going into the denser medium the light slows down and the angle of refraction is smaller.
3	Violet	Violet has the larger refractive index and is therefore deviated more.
4	The angle is 0 degrees and the ray goes straight back along its own path	A ray along the normal is reflected back along the normal, so both angles are zero.
5	20 degrees	The reflected ray turns through twice the angle the mirror turns.
6	Away from the normal	Going from denser to less dense the light speeds up and the angle of refraction is larger.
7	No, because 45 degrees is below the critical angle and most of the light refracts out	Total internal reflection needs the angle of incidence to exceed the critical angle.
8	2×10⁸ m/s	Divide 3×10⁸ by 1.5.
9	The colours recombine into white light	The second prism deviates in the opposite sense and cancels the first, which shows white light is a mixture.
10	A plane mirror forms a virtual image: the reflected rays only appear to come from behind the mirror and never really meet, so no screen catches it.	The difference between real and virtual images is a standard exam point.

04　What to do after marking

After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
Repeat the same item two days later; move to the next paper only when both attempts are correct.
Parents only need the answer and note columns; there is no need to explain every item.

For light questions ask three things: whether angles are measured from the normal, whether light goes from a denser to a less dense medium or the other way, and how many refractions occur.Tutor Registration →

Questions and answers are written originally by the TutorZone team and are not taken from any school, publisher or examination authority paper. Every value is checked by computer.