Eugene Kim

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Radiometer

• Eugene Kim
• Seung Min Kim

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What is Radiometer?

• Radiometer is a device that measures the
  intensity of radiant energy.
• It consists a partially evacuated glass bulb
  containing lightweight revolving vanes, each
  blackened on one side.
• This radiometer is also called Crookes Radiometer
  or light mill.

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Transformation of Energy Light Energy (Kinetic
Energy) ? Mechanical Energy (Kinetic Energy)
The vanes rotate when exposed to light, with
faster rotation for more intense light. The vane
turns toward the white side of the vanes.
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How does radiometer change light energy into
mechanical energy?

• If a plate is kept hotter on one side than the
  other, the gas flows
• through from the cooler to the hotter side.
• The black side absorbs light and heat while white
  side reflects light and heat.

• The pressure difference causes the vane to move
  cold side forward, which is the white side.