Match the following items. 1.
uses a lens to gather and focus light
refracting telescope
2. separates starlight into wavelengths
radio telescopes
3. pick up faint-lighted stars
spectrograph
4. see binary stars
giant refractors
5. see behind nebulae dust
giant reflectors

the answer is either b or c

on passing the small ampere of electric current through the tube made of ar and hg of cfl generates uv rays which excites the fluorescent and thus emits the high radiation by consumption of just 5- 12 w in comparison to incandescent light which requires more power such as around 40 - 55 w to lighten.

moreover the life span of fluorescent or cfl is around 8000 h whereas the life span of incandescent is around 1200 h

hence, the building installed with incandescent lights bears more electricity bill.