A sun-like star is barely visible to naked-eye observers on earth when it is a distance of 7.0 light years, or 6.6 * 1016 m, away. The sun emits a power of 3.8 * 1026 W. Using this information, at what distance would a candle that emits a power of 0.20 W just be visible?

At a distance of 1376.49 candle emits 0.2 watt power

Explanation:

Distance between Sun and earth

Sun emits a power of

Power emitted by candle = 0.20 watt

We know that brightness is given by

So

So at a distance of 1376.49 candle emits 0.2 watt power

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