9702 · 7.4
Electromagnetic spectrum flashcards
Revision flashcards for Cambridge 9702 Electromagnetic spectrum (syllabus 7.4). Flip, recall, then mark a real past-paper question.
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List the components of the electromagnetic spectrum from longest to shortest wavelength.
Radiowaves, Microwaves, Infrared, Visible Light, Ultraviolet, X-Rays, Gamma Rays.
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What is the speed of all electromagnetic waves in a vacuum, and what symbol represents it?
Approximately `3.00 x 10^8 m s^{-1}`, represented by 'c'.
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What fundamental type of wave are all electromagnetic waves, and how does this relate to polarisation?
They are transverse waves, which means their oscillations can be restricted to a single plane, demonstrating polarisation.
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What is the approximate wavelength range for visible light within the electromagnetic spectrum?
Approximately 400 nm to 700 nm (or `4 x 10⁻⁷ m` to `7 x 10⁻⁷ m`).
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State the formula that links the speed, frequency, and wavelength of an electromagnetic wave in a vacuum.
$c = f\lambda$
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What does 'transverse wave' mean in the context of EM waves?
The oscillations (electric and magnetic fields) are perpendicular to the direction of energy transfer (wave propagation).
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How does frequency change as you move from radio waves to gamma rays?
Frequency increases (from very low for radio waves to very high for gamma rays).
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What is polarisation, and why is it important for understanding EM waves?
Polarisation is the restriction of a wave's oscillations to a single plane. It's crucial evidence that EM waves are transverse.
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If an electromagnetic wave has a long wavelength, what can be said about its frequency?
It will have a low frequency, because their product ($f\lambda$) must always equal the constant speed of light ($c$).