new way physics for al

a. The number of significant figures is 3.

b. 1 microwatt = 1 X 10-6 watt

1 cm2 = 1 X 10-4 m2

So, 0.050 microwatt/cm2 = 0.050 X (1 X 10-4) / (1 X 10-6) = 5 W/m2

c. The order of magnitude is 1.

d. The maximum possible error is 0.005

So, the percentage error = 0.005 / 0.050 X 100% = 10%

e. As power = Energy / time = Js-1 = kgm2s-2s-1 = kgm2s-3

So, the dimension of the quantity

= Power / Area

= kgm2s-3 / m2

= kgs-3

Leading zeros are not significant. For example, 0.00012 has two significant figures: 1 and 2.

(From wiki)