Two materials are tested with equal incident energies at two wavelengths. Reflection is negligible.
| Material | Energy absorbed at 500 nm500\ \mathrm{nm}500 nm | Energy absorbed at 1000 nm1000\ \mathrm{nm}1000 nm |
|---|---|---|
| P | 10% | 70% |
| Q | 40% | 20% |
A screen must transmit more visible light than infrared radiation. Of the screens satisfying this condition, the one transmitting the greatest percentage of visible light is required.
Which screen should be chosen?
P alone, transmitting 90%90\%90% of visible light and 30%30\%30% of infrared.
Q alone, transmitting 60%60\%60% of visible light and 80%80\%80% of infrared.
P followed by Q, transmitting 54%54\%54% of visible light and 24%24\%24% of infrared.
Q followed by P, transmitting 50%50\%50% of visible light and 10%10\%10% of infrared.
84 exam-style questions on Edexcel GCSE Physics 5.2 The electromagnetic spectrum, covering 5.2.1 Electromagnetic waves and refraction in glass (core practical), 5.2.2 Groups of the electromagnetic spectrum, 5.2.3 Wavelength-dependent behaviour of EM waves, and 5.2.4 Velocities of EM waves in different substances. Each one has a worked solution and a mark scheme showing where the marks go.