What candle power rating does the emergency signaling mirror have when used on a bright sunny day?

What candle power rating does the emergency signaling mirror have when used on a bright sunny day?

• A. When used on a bright sunny day the emergency signaling mirror has a reflective glare of 2 million candle power (visible up to 40 miles).
• B. 4 million candle power (visible up to 20 miles).
• C. 1 million candle power (visible up to 15 miles).
• D. 8 million candle power (visible up to 40 miles).

Answer: (D)

An emergency signaling mirror is designed to reflect sunlight with very high luminous intensity to attract attention at a distance. Candle power measures that brightness of the reflected beam. In bright daylight, the signal needs to be extremely bright to be seen far away, so the highest rating is used. Eight million candle power corresponds to a signal visible up to about forty miles under optimal conditions, which is why this option is the best. Lower brightness values would not be as easily seen at long range in strong sunlight.

An emergency signaling mirror is designed to reflect sunlight with very high luminous intensity to attract attention at a distance. Candle power measures that brightness of the reflected beam. In bright daylight, the signal needs to be extremely bright to be seen far away, so the highest rating is used. Eight million candle power corresponds to a signal visible up to about forty miles under optimal conditions, which is why this option is the best. Lower brightness values would not be as easily seen at long range in strong sunlight.