OCR GCSE Physics A (Gateway)
OCR GCSE Physics A P5.3 Wave Interaction Exam Questions
Free OCR GCSE Physics A exam questions for P5.3 Wave Interaction, with a mark scheme for every pack. Covers reflection, refraction, transmission and absorption of waves, ray diagrams, colour, specular and diffuse reflection, and convex and concave lenses.
P5.3 Wave Interaction exam questions
1 question pack of real past exam questions, each with its mark scheme. Do not stop after a few: answer as many as you can without notes, then mark every answer with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
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About OCR GCSE Physics A P5.3 Wave Interaction
P5.3 completes the P5 Waves in matter chapter of OCR Gateway Physics A. It covers what happens when waves meet a boundary between materials: reflection, refraction, transmission and absorption, and how these depend on wavelength and the materials involved. You need to construct ray diagrams for reflection and refraction and explain refraction in terms of a change in wave speed. The topic also covers colour, including why objects appear coloured and how filters work, the difference between specular and diffuse reflection, and ray diagrams for convex and concave lenses. Examiners like ray diagram completion, refraction explanations and colour questions with filters.
What you need to know
- Interactions at boundaries Waves can be reflected, refracted, transmitted or absorbed at a boundary. What happens depends on the wavelength and the materials.
- Reflection Angle of incidence = angle of reflection, measured from the normal. Specular reflection from smooth surfaces gives a clear image; diffuse reflection from rough surfaces scatters light.
- Refraction Waves change speed when they enter a new medium, causing a change of direction unless they meet the boundary along the normal. Light slowing down bends towards the normal; wavelength decreases but frequency is unchanged.
- Colour Opaque objects appear the colour of the light they reflect, absorbing the rest. White objects reflect all wavelengths; black objects absorb all. Filters transmit only certain colours.
- Lenses A convex lens brings parallel rays to a principal focus and can form real images; a concave lens spreads rays out and forms virtual images. Ray diagrams use rays through the centre and parallel to the axis.
- Practical Investigate refraction by shining a ray box through a rectangular glass block, marking incident and emergent rays, and measuring angles from the normal with a protractor.
Common mistakes in P5.3 Wave Interaction
- Measuring angles from the surface instead of the normal.
- Saying frequency changes during refraction. Only speed and wavelength change.
- Saying a red filter adds red to the light. It absorbs other colours and transmits red.
- Saying a green object looks green under red light. It absorbs red and reflects none, so it appears black.
- Drawing a concave lens converging rays. Concave lenses make parallel rays diverge.
Try three P5.3 Wave Interaction exam-style questions
1. Explain why light changes direction as it enters a glass block at an angle. (3 marks)
Show the mark scheme answer
Light slows down in glass; one side of the wavefront enters and slows before the other; so the wave changes direction, bending towards the normal.
2. A red book is viewed through a blue filter in white light. Explain what colour it appears. (3 marks)
Show the mark scheme answer
The book reflects only red light; the blue filter absorbs red light and transmits only blue; no light reaches the eye, so the book appears black.
3. Describe the difference between specular and diffuse reflection. (2 marks)
Show the mark scheme answer
Specular reflection is from a smooth surface, with reflected rays in one direction giving a clear image; diffuse reflection is from a rough surface, scattering light in many directions.
P5.3 Wave Interaction FAQs
What does OCR GCSE Physics A (Gateway Science) P5.3 Wave Interaction cover?
It covers reflection, refraction, transmission and absorption, ray diagrams, colour and filters, specular and diffuse reflection, and lenses.
Which paper is P5.3 examined on?
Topics P5 to P8 are assessed on Paper 2 (Foundation) or Paper 4 (Higher), which can also draw on knowledge from P1 to P4 and practical skills.
How do I get full marks on ray diagrams?
Use a ruler and sharp pencil, draw the normal as a dashed line at right angles to the surface, add arrows to every ray and measure angles from the normal.
