The angle of twist of shaft is
A
Directly proportional to (shaft diameter)<sup>2</sup>
B
Inversely proportional to (shaft diameter)<sup>2</sup>
C
Directly proportional to (shaft diameter)<sup>4</sup>
D
Inversely proportional to (shaft diameter)<sup>4</sup>
Correct Answer: Inversely proportional to (shaft diameter)<sup>4</sup>