CIE iGCSE Co-Ordinated Science P3.2.1 Reflection of light Exam Style Questions Paper 1
▶️ Answer/Explanation
In the law of reflection:
- The angle of incidence (\( i \)) is the angle between the incident ray and the normal (the line perpendicular to the mirror surface at the point of incidence).
- The angle of reflection (\( r \)) is the angle between the reflected ray and the normal.
- The angle of incidence is equal to the angle of reflection (\( i = r \)).
Looking at the diagrams, we need the one where the normal is drawn as a dashed line perpendicular to the mirror, with angle \( i \) between the incident ray and the normal, and angle \( r \) between the reflected ray and the normal. In Diagram D, the normal is correctly drawn, and both angles are correctly labelled with respect to the normal. In the other diagrams, the angles are incorrectly placed or the normal is missing.
✅ Answer: (D)
▶️ 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
The angle of incidence is measured between the incident ray and the normal (the line perpendicular to the mirror surface).
If the angle between the ray and the mirror surface is 40°, then the angle with the normal is \(90° – 40° = 50°\).
✅ Answer: (B)
If the angle between the ray and the mirror surface is 40°, then the angle with the normal is \(90° – 40° = 50°\).
✅ Answer: (B)
▶️ Answer/Explanation
The angle of incidence is measured between the incident ray and the normal (an imaginary line perpendicular to the mirror). In the diagram, the angle between the ray and the mirror surface is 30°, so the angle with the normal is 90° − 30° = 60°. The law of reflection states that the angle of reflection equals the angle of incidence, so the angle of reflection is also 60°.
✅ Answer: (C)
✅ Answer: (C)
▶️ Answer/Explanation
In a plane mirror, the image formed is always the same size as the object, never smaller.
The image is also upright, laterally inverted, and the same distance behind the mirror as the object is in front of it.
Statement B is not correct, since the image is not smaller than the student.
✅ Answer: (B)
The image is also upright, laterally inverted, and the same distance behind the mirror as the object is in front of it.
Statement B is not correct, since the image is not smaller than the student.
✅ Answer: (B)