Physics XI Notes for Physics Notes

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Photometry- Old is Gold

  1. Why does the illuminance of a surface decrease as it moved away from the light source?
  2. What is the meaning of Luminous intensity?
  3. Define luminous flux. State its unit of measurement.
  4. What are the factors on which the illuminance of a surface depends?
  5. Define luminous efficiency of a source of light and give its SI unit.
  6. What is the difference between lumen and lux?
  7. Define illuminance. Name the factor upon which it depends.
  8. The sun is less bright in morning and in evening as compared to that at noon although its distance from the observer is almost the same. Why?
  9. Distinguish between illuminance and luminance.

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