0

From a textbook of recent publication;

"The average radiation on the Earth’s surface is $340 W m^{−2}$."

I get the 340W. I presume m is meters. How does a minus 2 affect a meter, rather a square meter?

Randall
  • 18,542
  • 2
  • 24
  • 47
Bcwilmot
  • 1

1 Answers1

1

It should be read as "per" and without the negative. So, in your case, "watts per square meter." You do the same thing with "miles per hour," which is $$ \frac{\text{miles}}{\text{hour}} = \text{miles} \cdot \text{hour}^{-1} $$

Randall
  • 18,542
  • 2
  • 24
  • 47
  • So is the negative sign a typo? – Bcwilmot Sep 19 '18 at 19:09
  • NO, that's what it means. Multiplication by negative exponents means dividing by the same power (without the minus sign). – Randall Sep 19 '18 at 19:09
  • What is the difference between m2 and m-2 ? – Bcwilmot Sep 19 '18 at 19:10
  • I own 2 square meters of property, and it cost me $5 PER square meter. The first has units $m^2$ (how much I own) and the second $\frac{\text{dollars}}{m^2} = \text{dollars}\cdot m^{-2}$ (the rate at which I paid for it). – Randall Sep 19 '18 at 19:10