A square aluminum rod is 1 m long and 5 mm on edge. What must be the radiys of another aluminum rod whose length is 1 m and which has the same reistance as that of square Aluminum rod ?

Options

A. `1.4 mm`
B. `2.8 mm`
C. `4.2mm`
D. `5.6 mm`

Answer

B

Explanation

`R_("square")=(R_("circle")`
`(cancelphi cancell_(s))/(A_(s))=(cancelrhocancell_(c))/(A_(c))(1_(s)-1_(c))`
`(1)/(A_(s))=(1)/(A_(c))`
`A_(c)=A_(s)`
`pi r^(2)=5xx5xx10^(-6)`
`r^(2)=(25xx10^(-6))/(pi)`
`r=(5xx10^(-3))/(sqrt(3.14))=2.82 mm`