Yousuf A.

asked • 05/31/16

Power output

A question asks us to find power output of a single panel when its area is give as 9.5 and the radiation flux is given as 590 and efficiency is given as 26 percent. I managed to find power by 590*9.5=5605 but the mark scheme said the answer was 5600, so why is this?

Dan D.

I notice you have left out all your units... and many other assumptions have to be made to really sovle this problem.
Did it ask to round the answer to some digit?  The tens? hundreds?
Also, is the "panel" a solar panel ?  As some guesses:
Area = 9.5 m2 ?
Flux is 590 Watts/m2 ?
I would expect that the efficiency, 26%, would be included as a factor of 0.26 somewhere...  Something like:
  power out = 0.26 * 9.5 * 590 = 1457.3 Watts.
Round it to nearest 10:
  power out ~ 1460 Watts.
 
 
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05/31/16

Arturo O.

Yousuf,
 
I think you have to factor in the 26% efficiency:
 
Power = (Power / unit area)*(area)*(efficiency)
 
Power = 590 * 9.5 * 0.26 = 1457.3
 
But his is still different than the given answer.  Is there other information given in the problem?
 
ARTURO O.
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05/31/16

1 Expert Answer

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Mark O. answered • 06/03/16

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Simple: 9.5 and 590 each have only two significant figures, so the answer must not have more than that.  The calculated answer, 5605, has four significant figures, so you must truncate it (rounding up if necessary) to two, hence 5600 (the five and six are significant, but trailing zeroes are not).
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Yousuf A.

Thanks for clearing that doubt. I noticed that this concept is used heavily by AS level papers
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06/06/16

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