Electromagnetic spectrum
AQA GCSE Physics revision on Electromagnetic spectrum. Aligned to the AQA GCSE Physics 8463 specification. This bank has 8 practice questions on this topic.
Sample questions (3 of 8)
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Question 1
All electromagnetic waves travel at...
- A) The speed of sound
- B) The speed of light
- C) Different speeds depending on type
- D) 1 m/s
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Answer: The speed of light
3 x 10^8 m/s = 300,000 km/s = light goes round Earth ~7.5 times per second. Same speed for visible light, X-rays, radio waves, gamma rays, microwaves, etc. - all EM waves in vacuum. Slower in materials (refractive index). Wave equation v=f x lambda: since v is fixed, frequency + wavelength are inversely related across the spectrum.
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Question 2
From LOWEST frequency to HIGHEST, the EM spectrum order is...
- A) Radio, microwave, infrared, visible, ultraviolet, X-ray, gamma
- B) Gamma, X-ray, UV, visible, IR, microwave, radio
- C) Visible, IR, UV, microwave, radio, X-ray, gamma
- D) Radio, gamma, microwave, visible, X-ray, UV, IR
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Answer: Radio, microwave, infrared, visible, ultraviolet, X-ray, gamma
Low frequency / long wavelength: RADIO (km-m wavelengths), MICROWAVE (cm), INFRARED (heat we feel from a fire), VISIBLE LIGHT (the only kind we see directly, ~400-700nm), ULTRAVIOLET (sunburn), X-RAY (medical imaging), GAMMA (nuclear). Increasing frequency = increasing energy = more dangerous (above visible). Decreasing wavelength = same direction.
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Question 3
Which EM wave is used in mobile phones + WiFi?
- A) Gamma
- B) Microwave (radio range)
- C) X-ray
- D) Visible light
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Answer: Microwave (radio range)
Mobile phones use frequencies in the 600-3500 MHz range (microwave / very high-frequency radio). WiFi: 2.4 GHz and 5 GHz (microwave). 5G uses higher microwave frequencies (sub-6 GHz + mmWave above 24 GHz). These frequencies penetrate buildings reasonably + don't interact strongly with human tissue (lower energy than IR). Used for non-line-of-sight communication.
Want to test yourself on the remaining cards for this topic?
5 more questions on Electromagnetic spectrum — plus mistakes tracking and spaced repetition across the whole Physics spec.