2.3.7

Leslie's Cube & Other Radiation Experiments

Test yourself

Radiation Experiments

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Painted thermometer bulbs

  • Setup: Take two thermometers. Paint one bulb black and leave the other shiny silver. Place them side by side in front of a radiant heat source (like a heat lamp).
  • Observation: The black bulb thermometer rises in temperature more quickly than the shiny one.
  • Explanation: A black surface is a good absorber (and also a good emitter) of infrared radiation.
    • A shiny silver surface is a poor absorber (it tends to reflect radiation).
  • Conclusion: Surface colour and texture affect how well radiation is absorbed and emitted.
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Hot water in different coloured metal beakers

  • Setup: Fill two identical metal beakers with the same amount of hot water. One beaker is painted black, the other is left shiny silver. Measure how quickly the water cools.
  • Observation: The black beaker cools down faster than the shiny silver beaker.
  • Explanation: A black surface is a good emitter of infrared radiation, so it loses heat more quickly.
    • A shiny silver surface is a poor emitter, so it keeps the water hot for longer.
  • Conclusion: Black surfaces are good absorbers and emitters of radiation, while shiny surfaces are poor absorbers and emitters.

Jump to other topics

1Motion, Forces & Energy

1.1Physical Quantities & Measurement Techniques

1.2Motion

1.3Mass & Weight

1.4Density

1.5Forces: Effects of Forces

1.6Forces: Turning Effects of Forces

1.7Forces: Centre of Gravity

1.8Momentum

1.9Energy, Work, & Power: Energy

1.10Energy, Work & Power: Work

1.11Energy, Work & Power: Energy Resources

1.12Energy, Work & Power: Power

1.13Pressure

2Thermal Physics

3Waves

4Electricity & Magnetism

4.1Simple Phenomena of Magnetism

4.2Electrical Quantities: Electric Charge

4.3Electrical Quantities: Electric Current

4.4Electromotive Force & Potential Difference

4.5Electrical Quantities: Resistance

4.6Electrical Energy & Electrical Power

4.7Electric Circuits: Circuit Diagrams & Components

4.8Electric Circuits: Series & Parallel Circuits

4.9Electric Circuits: Action & Use

4.10Electrical Safety

4.11Electromagnetic Effects: Electromagnetic Induction

4.12Electromagnetic Effects: The A.C. Generator

4.13Magnetic Effect of a Current

4.14Force on a Current-Carrying Conductor

4.15Electromagnetic Effects: The D.C. Motor

4.16Electromagnetic Effects: The Transformer

5Nuclear Physics

6Space Physics

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