The polar moment of inertia of a hollow circular shaft of outer diameter (D) and inner diameter (d) is
1
\(\frac{\pi}{16}\times (D^3-d^3)\)
2
\(\frac{\pi}{16}\times (D^4-d^4)\)
3
\(\frac{\pi}{32}\times (D^4-d^4)\)
4
\(\frac{\pi}{64}\times (D^4-d^4)\)