Light and the electromagnetic spectrum

Revision questions with answers for P5 Light and the electromagnetic spectrum in Pearson Edexcel GCSE Combined Science (spec 1SC0). Practise with flashcards, a topic quiz, a random quiz across the course, 5 crosswords, or read every question and answer below.

1. Question 1 · Spec P5.7

   What type of waves are electromagnetic waves?

   Answer:

   Transverse waves.

2. Question 2 · Spec P5.7

   What speed do all electromagnetic waves have in a vacuum?

   Answer:

   Approximately 3.0 × 10⁸ m/s.

3. Question 3 · Spec P5.8

   What do electromagnetic waves transfer from source to observer?

   Answer:

   Energy, without requiring a material medium.

4. Question 4 · Spec P5.10

   List the electromagnetic groups from longest to shortest wavelength.

   Answer:

   Radio, microwaves, infrared, visible, ultraviolet, X-rays and gamma rays.

5. Question 5 · Spec P5.11

   How does frequency vary as electromagnetic wavelength decreases?

   Answer:

   Frequency increases because all electromagnetic waves have the same vacuum speed.

6. Question 6 · Spec P5.10

   List visible colours from longest to shortest wavelength.

   Answer:

   Red, orange, yellow, green, blue, indigo and violet.

7. Question 7 · Spec P5.12

   Why can human eyes not detect the whole electromagnetic spectrum?

   Answer:

   Their receptors respond only to the limited range called visible light.

8. Question 8 · Spec P5.11

   What does it mean that the electromagnetic spectrum is continuous?

   Answer:

   There are no gaps between its wavelengths; group boundaries divide a continuous range.

9. Question 9 · Spec P5.8

   Give an example demonstrating electromagnetic energy transfer.

   Answer:

   Infrared from a heater warms an absorbing surface.

10. Question 10 · Spec P5.11

    Find frequency for wavelength 0.20 m, using c = 3.0 × 10⁸ m/s.

    Answer:

    f = c/λ = 1.5 × 10⁹ Hz.

11. Question 11 · Spec P5.9 · Core practical

    What is the aim of the rectangular-glass-block core practical?

    Answer:

    Investigate how a light ray refracts when passing between air and glass.

12. Question 12 · Spec P5.9 · Core practical

    How is the normal drawn in the refraction practical?

    Answer:

    At 90° to the block surface at the ray's entry point.

13. Question 13 · Spec P5.9 · Core practical

    How does an oblique ray usually bend entering glass from air?

    Answer:

    Towards the normal.

14. Question 14 · Spec P5.9 · Core practical

    How does an oblique ray usually bend leaving glass for air?

    Answer:

    Away from the normal.

15. Question 15 · Spec P5.9 · Core practical

    What happens to a ray entering along the normal?

    Answer:

    Its direction does not change.

16. Question 16 · Spec P5.9 · Core practical

    How does the emerging ray relate to the incident ray for a parallel-sided block in air?

    Answer:

    It is parallel to the incident ray but usually displaced sideways.

17. Question 17 · Spec P5.9 · Core practical

    What is lateral displacement in the glass-block practical?

    Answer:

    The sideways shift between the incident ray's original path and the emergent ray.

18. Question 18 · Spec P5.14 · Higher only

    Why does light change direction at oblique entry into glass?

    Answer:

    Its speed changes at the boundary, changing the orientation of the wavefront.

19. Question 19 · Spec P5.14 · Higher only

    What happens to wavelength and frequency when light slows in glass?

    Answer:

    Wavelength decreases while frequency remains unchanged.

20. Question 20 · Spec P5.13 · Higher only

    Why may one material absorb infrared but transmit visible light?

    Answer:

    Absorption and transmission depend on both the material and the radiation's wavelength.

21. Question 21 · Spec P5.9 · Core practical

    Outline a method for tracing a ray through a glass block.

    Answer:

    Draw around the block, direct a narrow ray at it, mark incident and emergent paths, then remove it and join the entry and exit points.

22. Question 22 · Spec P5.9 · Core practical

    Why draw around the block before moving it?

    Answer:

    Its original position is needed to locate boundaries and draw the internal ray correctly.

23. Question 23 · Spec P5.9 · Core practical

    How are incidence and refraction angles measured?

    Answer:

    Between each ray and the normal, using a protractor, rather than from the surface.

24. Question 24 · Spec P5.9 · Core practical

    Which variables should be controlled when varying incidence angle?

    Answer:

    Use the same block material, surrounding medium and light source while keeping the block correctly aligned.

25. Question 25 · Spec P5.9 · Core practical

    Why use a narrow ray and thin pencil marks?

    Answer:

    They make the ray path and angle measurements more precise.

26. Question 26 · Spec P5.9 · Core practical

    Why repeat several different incidence angles?

    Answer:

    To identify a consistent pattern and check the behaviour is not based on one reading.

27. Question 27 · Spec P5.9 · Core practical

    What error occurs if the block is moved between marking ray positions?

    Answer:

    The recorded paths no longer correspond to the same boundaries, producing incorrect angles.

28. Question 28 · Spec P5.23 · Higher only

    How can radio waves be generated?

    Answer:

    Oscillating currents in electrical circuits produce electromagnetic radiation.

29. Question 29 · Spec P5.23 · Higher only

    What can an incoming radio wave induce in a circuit?

    Answer:

    An electrical oscillation at the wave's frequency.

30. Question 30 · Spec P5.24

    How can electron changes produce or absorb electromagnetic radiation?

    Answer:

    Moving between energy levels involves absorbing or emitting radiation of an appropriate frequency.

31. Question 31 · Spec P5.24

    Which atomic changes can produce gamma radiation?

    Answer:

    Changes in the energy state of the nucleus.

32. Question 32 · Spec P5.20

    How does potential electromagnetic hazard generally vary with frequency?

    Answer:

    It generally increases with increasing frequency.

33. Question 33 · Spec P5.21

    What is a hazard of excessive microwave exposure?

    Answer:

    Internal heating of body cells.

34. Question 34 · Spec P5.21

    What is a hazard of excessive infrared exposure?

    Answer:

    Heating that can cause skin burns.

35. Question 35 · Spec P5.21

    What can excessive ultraviolet exposure damage?

    Answer:

    Surface cells and eyes, increasing the risk of skin cancer and eye conditions.

36. Question 36 · Spec P5.21

    How can X-rays and gamma rays damage the body?

    Answer:

    Their ionising effects can damage cells and cause mutations.

37. Question 37 · Spec P5.21

    Why must exposure amount be considered alongside radiation type?

    Answer:

    Risk depends on how much radiation is absorbed as well as its properties.

38. Question 38 · Spec P5.22

    Give communication uses of radio waves.

    Answer:

    Broadcasting, communications and satellite transmissions.

39. Question 39 · Spec P5.22

    Give uses of microwaves.

    Answer:

    Cooking, communications and satellite transmissions.

40. Question 40 · Spec P5.22

    Give three uses of infrared radiation.

    Answer:

    Thermal imaging, cooking and television remote controls; security systems and communication are further examples.

41. Question 41 · Spec P5.22

    Which invisible radiation is used in many optical-fibre communication systems?

    Answer:

    Infrared radiation.

42. Question 42 · Spec P5.22

    Give three uses of visible light.

    Answer:

    Vision, photography and illumination.

43. Question 43 · Spec P5.22

    How is ultraviolet used in fluorescent lamps?

    Answer:

    It causes suitable materials to fluoresce, producing visible light.

44. Question 44 · Spec P5.22

    How can ultraviolet help detect security markings or forged notes?

    Answer:

    Suitable markings fluoresce under ultraviolet, revealing patterns not normally visible.

45. Question 45 · Spec P5.22

    How can ultraviolet help disinfect water?

    Answer:

    It damages microorganisms and reduces the number able to reproduce.

46. Question 46 · Spec P5.22

    Why can X-rays reveal bones in medical images?

    Answer:

    Bone absorbs X-rays differently from surrounding soft tissue, creating contrast.

47. Question 47 · Spec P5.22

    How are X-rays used outside medicine?

    Answer:

    They reveal internal structures in objects, such as luggage in airport security scanners.

48. Question 48 · Spec P5.22

    How can gamma rays sterilise food or medical equipment?

    Answer:

    They damage or kill microorganisms without requiring high-temperature treatment.

49. Question 49 · Spec P5.22

    How can gamma radiation be used in cancer care?

    Answer:

    It can help detect cancer in suitable procedures and be directed to kill cancer cells during treatment.

50. Question 50 · Spec P5.21

    How should a medical radiation procedure's value be assessed?

    Answer:

    Compare diagnostic or treatment benefit with exposure risks, using the lowest dose that achieves the clinical purpose.

More Pearson Edexcel GCSE Combined Science topics

• B1 Key concepts in biology
• B2 Cells and control
• B3 Genetics
• B4 Natural selection and genetic modification
• B5 Health, disease and the development of medicines
• B6 Plant structures and their functions
• B7 Animal coordination, control and homeostasis
• B8 Exchange and transport in animals
• B9 Ecosystems and material cycles
• C1 Key concepts in chemistry
• C2 States of matter and mixtures
• C3 Chemical change
• C4 Extracting metals and equilibria
• C6 Groups in the periodic table
• C7 Rates of reaction and energy changes
• C8 Fuels and Earth science
• P1 Key concepts of physics
• P2 Motion and forces
• P3 Conservation of energy
• P4 Waves
• P5 Light and the electromagnetic spectrum
• P6 Radioactivity
• P8 Energy - forces doing work
• P9 Forces and their effects
• P10 Electricity and circuits
• P12 Magnetism and the motor effect
• P13 Electromagnetic induction
• P14 Particle model
• P15 Forces and matter

Other Combined science courses: AQA GCSE Combined Science: Trilogy.