Question

Two rods A and B of the same material and length have radii $\mathrm { r } _ { 1 }$and respectively. When they are rigidly fixed at one end and twisted by the same torque applied at the other end, the ratio

• A.
• B.
• C.
• D.

Answer 1

Answer: (C)

Answer 2

: A rod of length L and radius r fixed at one end and twisted by applying a torque $\tau$at the other end, then the angle of twist $\theta$is given by

Where $\tau$ and $\eta$are same for both the wires

$\therefore \theta \propto \frac { 1 } { r ^ { 4 } } \quad \therefore \frac { \theta _ { 1 } } { \theta _ { 2 } } = \left( \frac { r _ { 2 } } { r _ { 1 } } \right) ^ { 4 }$