CIE iGCSE Co-Ordinated Science P3.2.2 Refraction of light Exam Style Questions Paper 1
▶️ Answer/Explanation
Angle X is measured between the incident ray and the normal, so it is the angle of incidence. Angle Y is measured between the refracted ray (the ray that has passed into the water) and the normal, so it is the angle of refraction. Reflection would involve a ray bouncing off the surface back into the same medium, which is not shown in the diagram. Therefore, option B correctly identifies angle X as the angle of incidence and angle Y as the angle of refraction.
✅ Answer: (B)
✅ Answer: (B)
▶️ Answer/Explanation
When light travels from air into a denser medium like glass, it slows down and bends towards the normal. The angle of incidence (\(i\)) is the angle between the incident ray and the normal, while the angle of refraction (\(r\)) is the angle between the refracted ray and the normal. Since the light bends towards the normal, \(r\) is smaller than \(i\). Diagram B correctly shows the light bending towards the normal with \(i\) and \(r\) correctly labelled.
✅ Answer: (B)
✅ Answer: (B)
▶️ Answer/Explanation
When light enters a glass block from air, it slows down and bends towards the normal (refraction). When it leaves the glass block back into air, it speeds up and bends away from the normal, emerging parallel to its original direction but laterally displaced. Arrow C correctly shows this path.
✅ Answer: (C)
✅ Answer: (C)
▶️ Answer/Explanation
The angle of refraction must always be measured between the refracted ray and the normal, which is perpendicular to the boundary.
In this diagram, angle Q is marked between the ray and the boundary surface itself, not the normal.
Since the normal is at 90° to the surface, the true angle from the normal is \(90° – Q\).
✅ Answer: (D)
In this diagram, angle Q is marked between the ray and the boundary surface itself, not the normal.
Since the normal is at 90° to the surface, the true angle from the normal is \(90° – Q\).
✅ Answer: (D)
▶️ Answer/Explanation
Light travels more slowly in glass than in air because glass is the denser optical medium.
When light passes from glass into the less dense air, it speeds up and bends away from the normal.
The arrow that bends away from the normal line at the glass-air boundary shows the correct refracted path.
✅ Answer: (D)
When light passes from glass into the less dense air, it speeds up and bends away from the normal.
The arrow that bends away from the normal line at the glass-air boundary shows the correct refracted path.
✅ Answer: (D)