Question

Calculate the solid angle subtended by the periphery of an area of 1 cm² at a point situated symmetrically at a distance of 5 cm from the area.

Answer 1

As solid angle Ω = \(\frac{Area}{(distance)^2}\)

[Area = 1cm² , distance = 5cm]

= \(\frac{1cm^2}{(5cm)^2}\)

= \(\frac{1}{25}\) = 4 × 10^-2 steradian.

Solid angle, Ω = 4 × 10^-2 steradian