A thin spherical shell of internal diameter d is subjected to an internal pressure p. If $${\sigma _{\text{t}}}$$ is the tensile stress for the shell material, then thickness of shell is equal to
A
$$\frac{{{\text{pd}}}}{{{\sigma _{\text{t}}}}}$$
B
$$\frac{{{\text{pd}}}}{{2{\sigma _{\text{t}}}}}$$
C
$$\frac{{{\text{pd}}}}{{3{\sigma _{\text{t}}}}}$$
D
$$\frac{{{\text{pd}}}}{{4{\sigma _{\text{t}}}}}$$
Correct Answer: $$\frac{{{\text{pd}}}}{{4{\sigma _{\text{t}}}}}$$