Edexcel International GCSE Physics
Edexcel International GCSE Physics Section 3: Waves Exam Questions
Free Edexcel International GCSE Physics exam questions for Section 3: Waves, with a mark scheme for every pack. Covers wave properties, wave equations, the electromagnetic spectrum, reflection, refraction, total internal reflection, sound and the Doppler effect.
Section 3: Waves exam questions
2 question packs 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 Edexcel International GCSE Physics Section 3: Waves
Section 3 of Edexcel International GCSE Physics covers the properties of waves, the electromagnetic spectrum, light and sound. You need to describe transverse and longitudinal waves, use v = f x lambda and f = 1 / T, and explain the Doppler effect. The electromagnetic spectrum part covers the order of the waves, their uses and their hazards. Light covers reflection, refraction, refractive index, critical angle and total internal reflection in optical fibres. Sound covers frequency range of hearing, echoes and using an oscilloscope to show frequency and amplitude. Examiners regularly test Snell's law calculations, critical angle, ray diagrams and practicals such as investigating refraction in a glass block.
What you need to know
- Wave basics Transverse waves oscillate at right angles to the direction of travel; longitudinal waves oscillate parallel to it. Waves transfer energy and information without transferring matter.
- Wave equations Wave speed = frequency x wavelength (v = f lambda) and frequency = 1 / time period (f = 1 / T).
- Doppler effect When a wave source moves towards an observer the waves are squashed, so observed frequency increases and wavelength decreases; moving away does the opposite.
- EM spectrum Radio, microwaves, infrared, visible, ultraviolet, X-rays, gamma rays, all travelling at the same speed in a vacuum. Hazards include internal heating from microwaves, skin burns from infrared, damage to eyes and skin cancer from UV, and cancer or mutation from X-rays and gamma rays.
- Refraction and refractive index Light changes speed and direction entering a different medium. Refractive index n = sin i / sin r.
- Total internal reflection Occurs when light in a denser medium hits the boundary at an angle greater than the critical angle, where sin c = 1 / n. Used in optical fibres and prisms.
- Sound Sound is longitudinal and needs a medium. Human hearing range is about 20 Hz to 20 000 Hz. On an oscilloscope, higher frequency gives more waves on the screen and larger amplitude gives a louder sound.
Common mistakes in Section 3: Waves
- Saying the frequency changes when light refracts. Frequency is unchanged; speed and wavelength change.
- Measuring angles of incidence from the surface. Measure them from the normal.
- Using sin c = n instead of sin c = 1 / n. The critical angle always has a sine less than 1.
- Thinking sound can travel through a vacuum. Sound needs particles to travel.
- Mixing up wavelength and amplitude on a diagram. Amplitude is measured from the rest position to a peak, not peak to trough.
Try three Section 3: Waves exam-style questions
1. Light enters a glass block with an angle of incidence of 40 degrees and an angle of refraction of 25 degrees. Calculate the refractive index. (3 marks)
Show the mark scheme answer
n = sin i / sin r; = sin 40 / sin 25 = 0.643 / 0.423; = 1.52.
2. A glass has a refractive index of 1.5. Calculate its critical angle. (2 marks)
Show the mark scheme answer
sin c = 1 / n = 1 / 1.5 = 0.667; c = 42 degrees.
3. Describe how the Doppler effect changes the sound heard as an ambulance drives towards and then away from you. (3 marks)
Show the mark scheme answer
As it approaches, the waves are compressed so wavelength decreases and frequency increases (higher pitch); as it moves away, the waves are stretched, wavelength increases and frequency decreases (lower pitch).
Section 3: Waves FAQs
What does Edexcel International GCSE Physics Section 3 Waves cover?
It covers wave properties, wave equations, the Doppler effect, the electromagnetic spectrum, reflection, refraction, total internal reflection and sound.
Which paper is Section 3 examined on?
Content from this section can appear on both Paper 1 and Paper 2; statements shown in bold in the specification are only assessed on Paper 2.
What equations do I need for Waves?
Learn v = f lambda, f = 1 / T, n = sin i / sin r and sin c = 1 / n.
