A furnace with an aperture of 20-mm diameter and emis- sive power of 3. 72 x 105 W/m, is used to calibrate a heat flux gage having a sensitive area of 1. 6 × 10-5 m2. (a) At what distance, measured along a normal from the aperture, should the gage be positioned to receive irradiation of 1000 W/m2? (b) If the gage is tilted off normal by 20°, what will be its irradiation?
