This common misconceptions covers Common Misconceptions within Electromagnetic Spectrum for GCSE Physics. Revise Electromagnetic Spectrum in Waves for GCSE Physics with 15 exam-style questions and 15 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 8 of 13 in this topic. Use this common misconceptions to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 8 of 13
Practice
15 questions
Recall
15 flashcards
⚠️ Common Misconceptions
Misconception 1: "Microwaves cook food from the inside out"
Microwaves are absorbed by water molecules in food, causing them to vibrate and heat up. Penetration depth is typically only a few centimetres, so the outside heats first — the centre cooks by conduction from the hot outside layer. Microwaves do NOT pass through food to heat the centre directly.
Misconception 2: "All radiation is dangerous"
Only ionising radiation (UV, X-rays, gamma) is dangerous in the DNA-damaging sense. Radio waves and microwaves are non-ionising — they cannot break chemical bonds. Your phone emits microwave radiation, but at such low power it does not cause ionisation. The hazard from microwaves is heating, not ionisation.
Misconception 3: "Light travels through glass at the same speed as in air"
All EM waves travel at c = 3 × 10⁸ m/s only in a vacuum. In any other medium (glass, water, air), they slow down. Light in glass travels at roughly 2 × 10⁸ m/s. This slowdown is what causes refraction.