Recent developments in LEDs permit them to be used in environmental and task lighting. LEDs have many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching. Light-emitting diodes are now used in applications as diverse as aviation lighting, automotive headlamps, advertising, general lighting, traffic signals, camera flashes and lighted wallpaper. As of 2015[update], LEDs powerful enough for room lighting remain somewhat more expensive, and require more precise current and heat management, than compact fluorescent lamp sources of comparable output.

Electroluminescence as a phenomenon was discovered in 1907 by the British experimenter H. J. Round of Marconi Labs, using a crystal of silicon carbide and a cat's-whisker detector. Soviet inventor Oleg Losev reported creation of the first LED in 1927. His research was distributed in Soviet, German and British scientific journals, but no practical use was made of the discovery for several decades. Kurt Lehovec, Carl Accardo and Edward Jamgochian, explained these first light-emitting diodes in 1951 using an apparatus employing SiC crystals with a current source of battery or pulse generator and with a comparison to a variant, pure, crystal in 1953.

Now, provide a numbered list of answers to these questions:

1. What is the article about?
2. What does this stand for?
3. When were they first created?
4. By whom?
5. What was his occupation?
6. What became of his discovery?
7. Were other scientists responsible in the advancement?
8. How many?
9. Can you name one?
10. When did they help advance the theory?
11. How are they applied today?
12. any other ways?
13. What are those?
14. Are they cheap?
15. Are they hotter than standard bulbs?
16. While producing the same light?
17. Do they consume more power than standard bulbs?
18. Do they last longer?
19. Can they be seen on walls?
20. How do they benefit a photographer?

Numbered answers:
1. LEDs
2. Light-emitting diodes
3. 1927
4. Oleg Losev
5. inventor
6. was distributed in Soviet, German and British scientific journals
7. yes
8. Three
9. Kurt Lehovec
10. 1951
11. environmental and task lighting.
12. yes
13. aviation lighting, automotive headlamps, advertising, general lighting, traffic signals, camera flashes and lighted wallpaper
14. no
15. yes
16. no
17. no
18. yes
19. yes
20. camera flashes