A cylindrical conductor of diameter 0.1 mm carries a current of 90 mA. The current density( in `Am^(-2)`) is `pi= 3`

Options

A. `1.2 xx 10^(7)`
B. `6 xx 10^(6)`
C. `3 xx 10^(6)`
D. `2.4 xx 10^(7)`

Answer

A

Explanation

Here, current = 90 mA, diameter of cylindrical conductor=0.1 mm, `pi=3`
`"The current density"=(I)/(pi(D^(2))/(4))=(90 xx 10^(-3))/(3 xx ((0.1 xx 10^(-3))^(2))/(4))`
`=1.3 xx 10^(7) A m^(-2)`