(a) The amount of solar energy received per second by one metre square area of the near earth space (exposed perpendicularly to the sun rays) at an average distance between the sun and the earth, is known as solar constant. Its value is 1.4kJ/s/m2.
(b) Area, A=5m2;time,t=10rnin=600sec,E=4200kJ.
Solar constant =E/(Axt)
=4200/(5×600)
=1.4kJ/s/m2