Question

An isotropic point source of light is suspended h metre vertically above the centre of circular table of radius r metre. Then, the ratio of illumenances at the centre to that at the edge of the table is

• A. $1+(\frac {r^2}{h^2})$
• B. $1+(\frac {h^2}{r^2})$
• C. $\\{1+\frac {r^2}{h^2}\\}^{\frac 32}$
• D. $\\{1+\frac {h^2}{r^2}\\}^{\frac 32}$

Answer 1

Answer: (C)

$\\{1+\frac {r^2}{h^2}\\}^{\frac 32}$

Answer 2

The correct option is (C): $\\{1+\frac {r^2}{h^2}\\}^{\frac 32}$.