Question

two wires A and B of the same material and equal lengths but of radii r and soldered coaxially the free end of B is twisted by an angle the ratio of the twist at the junction and angle phi is

Answer 1

$\text{Angle of twist is inversely proportional to the fourth square of the radius}\\ \theta=\dfrac{k}{r^4}\\ \text{k is constant}\\ \theta_A=\dfrac{k}{r_A^4}\\ \theta_B=\dfrac{k}{r_B^4}\\ \dfrac{\theta_A}{\theta_B}=(\dfrac{r_B}{r_A})^4$