Radiation as infrared electromagnetic waves, what affects absorption and emission, why good absorbers are good emitters, and the design of vacuum flasks and solar water heaters, and the greenhouse effect.
6 narrated scenes. Press play, listen and read along — the points appear as they are explained. Use ‹ Prev / Next › or the scene bar to jump to any scene.
The Sun’s energy crosses 150 million kilometres of empty space to warm your skin. Only radiation can do that, and the same idea keeps coffee hot in a flask.
Narration uses your device’s built-in voice. No sound? Switch to “Captions only” — the captions advance on their own.
Copy these into your notebook in your own words — that is how they stick.
Infrared electromagnetic waves; no medium needed; speed of light.
Dull black.
Shiny white or silver (good reflector).
Texture and surface area.
Good absorbers are good emitters.
Vacuum (no conduction/convection); silvered walls (less radiation); insulating stopper.
Black panel absorbs; glass cover and insulation; convection to the tank.
CO₂ and other gases trap infrared; more CO₂ gives global warming.
3 quick games on this lesson. Earn XP and badges as you play — your best score for each game is saved. Games are for practice and do not change your exam readiness. More games in the Physics Arcade.
8 items modelled on real CSEC Paper 1 questions. Choose one answer for each, then check. Aim for 80% or better. Work each item on paper first.
Write full answers, then reveal the mark scheme and tick the points you earned (15 marks in total). Show all your working — method marks count. Your answers are saved on this device.
Question 1 [15 marks]
A vacuum flask keeps drinks hot. A student also compares a dull black can and a shiny silver can of hot water.
(a) (a) State what is meant by thermal radiation. [2]
(b) (b) Explain how each feature of the vacuum flask reduces heat loss: (i) the vacuum; (ii) the silvered surfaces; (iii) the stopper. [3]
(c) (c) Both cans contain 200 g of water at 90 °C. State which cools faster and explain. [3]
(d) (d) State three variables that must be controlled in the investigation. [3]
(e) (e) Explain why a solar water heater panel is painted dull black. [2]
(f) (f) Explain how increasing carbon dioxide in the atmosphere leads to global warming. [2]
Find these in your own past-paper booklets for extra timed practice. Items above are written in the style of these papers; any adapted from a specific question say so.