OCR · A-Level · Physics

    Course version: H556 · Version from Sept 2015

    (b) orders of magnitude of wavelengths of the principal radiations from…

    Full specification wording

    Electromagnetic waves: (b) orders of magnitude of wavelengths of the principal radiations from radio waves to gamma rays

    You need approximate orders of magnitude for the wavelength of each principal region.

    Checked against the OCR H556 specification (opens in a new tab) on .

    • Point 2 of 6
    • 2 key terms

    Study notes

    From the checked teaching notes for this specification point.

    The idea

    You need approximate orders of magnitude for the wavelength of each principal region. Radio waves extend from about 10⁻¹ m to 10⁴ m or more; microwaves about 10⁻³ m to 10⁻¹ m; infrared about 7 × 10⁻⁷ m to 10⁻³ m; visible light about 4 × 10⁻⁷ m to 7 × 10⁻⁷ m; ultraviolet about 10⁻⁸ m to 4 × 10⁻⁷ m; X-rays about 10⁻¹¹ m to 10⁻⁸ m; gamma rays shorter than about 10⁻¹¹ m. These are orders of magnitude, not sharp boundaries, and regions overlap slightly.

    What earns the marks

    • Radio waves: roughly 10⁻¹ m to 10⁴ m and beyond.
    • Microwaves: roughly 10⁻³ m to 10⁻¹ m.
    • Infrared: roughly 10⁻⁷ m to 10⁻³ m.
    • Visible light: roughly 4 × 10⁻⁷ m to 7 × 10⁻⁷ m.
    • Ultraviolet: roughly 10⁻⁸ m to 4 × 10⁻⁷ m.
    • X-rays: roughly 10⁻¹¹ m to 10⁻⁸ m.
    • Gamma rays: shorter than about 10⁻¹¹ m.

    Common mistakes and how to put them right

    • Treating the boundaries as exact.

      Put it right: They are orders of magnitude and adjacent regions overlap.

    • Confusing infrared and ultraviolet ranges.

      Put it right: Infrared is longer than visible, ultraviolet shorter.

    • Placing X-rays at longer wavelengths than ultraviolet.

      Put it right: X-rays are shorter than ultraviolet.

    • Forgetting that gamma rays have the shortest wavelengths, below about 10⁻¹¹ m.

    Exam tips

    • Anchor visible light at about 5 × 10⁻⁷ m and work outwards in powers of ten.
    • Compare the exponent first, then the coefficient, when judging which region a wavelength belongs to.
    • Remember that shorter wavelength means higher frequency and higher photon energy.
    • Watch for values given in nanometres or picometres and convert to metres before comparing.

    Try the lesson

    The start of the Electromagnetic waves: (b) orders of magnitude of wavelengths of the principal radiations from radio waves to gamma rays lesson, made from checked teaching notes for this specification point.

    Listen

    You need approximate orders of magnitude for the wavelength of each principal region. Radio waves extend from about 10⁻¹ m to 10⁴ m or more; microwaves about 10⁻³ m to 10⁻¹ m; infrared about 7 × 10⁻⁷ m to 10⁻³ m; visible light about 4 × 10⁻⁷ m to 7 × 10⁻⁷ m; ultraviolet about 10⁻⁸ m to 4 × 10⁻⁷ m; X-rays about 10⁻¹¹ m to 10⁻⁸ m; gamma rays shorter than about 10⁻¹¹ m. These are orders of magnitude, not sharp boundaries, and regions overlap slightly. A strong answer earns marks for these points. Radio waves: roughly 10⁻¹ m to 10⁴ m and beyond. Microwaves: roughly 10⁻³ m to 10⁻¹ m. Infrared: roughly 10⁻⁷ m to 10⁻³ m. Visible light: roughly 4 × 10⁻⁷ m to 7 × 10⁻⁷ m. Exam tip: Anchor visible light at about 5 × 10⁻⁷ m and work outwards in powers of ten.

    See it

    A left-to-right flowchart of seven boxes joined by arrows. The first box is labelled radio waves, about 10⁻¹ m to 10⁴ m and beyond. An arrow leads to microwaves, about 10⁻³ m to 10⁻¹ m. An arrow leads to infrared, about 10⁻⁷ m to 10⁻³ m. An arrow leads to visible light, about 4 × 10⁻⁷ m to 7 × 10⁻⁷ m. An arrow leads to ultraviolet, about 10⁻⁸ m to 4 × 10⁻⁷ m. An arrow leads to X-rays, about 10⁻¹¹ m to 10⁻⁸ m. A final arrow leads to gamma rays, shorter than about 10⁻¹¹ m.
    It shows the principal regions of the electromagnetic spectrum in order from the longest to the shortest wavelengths, with their approximate orders of magnitude.

    Put it in order

    Put these steps in the order they happen.

    1. 1. Gamma rays: shorter than about 10⁻¹¹ m
    2. 2. X-rays: about 10⁻¹¹ m to 10⁻⁸ m
    3. 3. Infrared: about 10⁻⁷ m to 10⁻³ m
    4. 4. Ultraviolet: about 10⁻⁸ m to 4 × 10⁻⁷ m
    5. 5. Radio waves: about 10⁻¹ m to 10⁴ m and beyond
    6. 6. Microwaves: about 10⁻³ m to 10⁻¹ m
    7. 7. Visible light: about 4 × 10⁻⁷ m to 7 × 10⁻⁷ m

    Key words

    Say what each word means before you turn the card.

    Orders of magnitude across the spectrum

    Try answering aloud or in your head before turning the card.

    Overlapping region boundaries

    Try answering aloud or in your head before turning the card.

    See every definition
    Orders of magnitude across the spectrum
    Approximate wavelength ranges for each principal region, not sharp boundaries, with adjacent regions overlapping slightly.
    Overlapping region boundaries
    The boundaries between regions are orders of magnitude rather than exact, and adjacent regions overlap slightly.

    Label the diagram

    Some boxes have lost their names. Pick the right name for each number.

    The diagram again, with 3 boxes numbered instead of named. A left-to-right flowchart of seven boxes joined by arrows. The first box is labelled radio waves, about 10⁻¹ m to 10⁴ m and beyond. An arrow leads to microwaves, about 10⁻³ m to 10⁻¹ m. An arrow leads to infrared, about 10⁻⁷ m to 10⁻³ m. An arrow leads to visible light, about 4 × 10⁻⁷ m to 7 × 10⁻⁷ m. An arrow leads to ultraviolet, about 10⁻⁸ m to 4 × 10⁻⁷ m. An arrow leads to X-rays, about 10⁻¹¹ m to 10⁻⁸ m. A final arrow leads to gamma rays, shorter than about 10⁻¹¹ m.

    • 1Box 1

    • 2Box 2

    • 3Box 3

    0 of 3 labelled

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