Question

11. One light year is
A. equal to 365 days
B. equal to 365 meters
C. equal to 2.9 million miles
D. equal to 9.466 trillion kilometers

12. Light has both
A. wave and particle properties
B. magnetic and electric field properties
C. mysterious and unknown properties
D. all of the above

13. Hawaii's Mauna Kea was chosen for the Keck I and II telescopes because
A. the atmosphere blocks X-rays
B. warm air is more transparent than cold air
C. the air is free of dust and dry
D. at 13,800 feet, the telescopes are closer to the stars

14. We place telescopes in space because
A. the atmosphere blocks radio waves
B. satellites are stationary
C. the atmosphere blocks X-rays
D. satellite telescopes are closer to the stars

15. The temperature of orange hot lava flows is about
A. 1,000 Kelvin
B. 3,000 Kelvin
C. 6,000 Kelvin
D. 9,000 Kelvin

Answer 1

11. Answer : D

One light year is defined as the distance travelled by light in one earth year . One light year is equal to 6 trillion miles or 9 trillion kilometres.

Speed of light (c) is equal to 1,86,000 miles per second or 1.86 ×105 seconds per miles or 3.00 ×105 per km

and light year(d) is calculated from c×t

C is speed of light and t is number of seconds in a year .

t = 31,536,000 seconds in a year or 3.154 ×107 seconds .

d = {3.00× 105 } × { 3.154×107 }

d = 9.46 ×1012 kilometres or 9.46 trillion kilometres