1. Shown in the left side figure, is the differential solid angle d2 subtended by thedifferential area dA when viewed from point P. We define the solid angle at pointP as the projection of the surface on a sphere of unit radius surrounding the point.Thus, the differential solid angle d2 subtended by surface dA in the left side fig-ure below is given by dN= dQ = (dA )/r² . a) Use this definition to computethe solid angle Q subtended by a circular disk of radius a at a point P that is lo-cated a distance R from the disk, where P lies on the normal n passing through thecenter of the disk, as shown in the right figure. b) Find 2 as a → o. [Ans.: b)Hemisphere].Questions and Problems593RndAP!

Asper the question we have to find the total solid angle Ω subtended by the circular disc of radius…

1. Shown in the left side figure, is the differential solid angle d2 subtended by the differential area dA when viewed from point P. We define the solid angle at point P as the projection of the surface on a sphere of unit radius surrounding the point. Thus, the differential solid angle d2 subtended by surface dA in the left side fig- ure below is given by dN= dn = (dA ·Q)/r² . a) Use this definition to compute the solid angle N subtended by a circular disk of radius a at a point P that is lo- cated a distance R from the disk, where P lies on the normal n passing through the center of the disk, as shown in the right figure. b) Find 2 as a → ∞. [Ans.: b) Hemisphere].