Question

1.
(
denoted as 0.
(ii) Solid angle(d2): This is the 3-dimensional
analogue of de and is defined as the area
of a portion of surface of a sphere to
the square of radius of the sphere. Thus
de dA/r is the solid angle subtended by
area ds at O as shown in Fig. 1.1 (b). It
is measured in steradians (sr). A sphere of
radius r has surface area 4er. Thus, the
solid angle subtended by the entire sphere
at its centre is 2 = 4rº/r2 = 410 sr.​

Answer 1

Answer:

Explanation:

The solid angle of a sphere measured from any point in its interior is 4π sr, and the solid angle subtended at the center of a cube by one of its faces is one-sixth of that, or 2π3 sr.

In SI base units: m2/m2

Common symbols: Ω

Other units: Square degree