At a distance of 10 cm from a long straight wire carrying current, the magnetic field is `4xx10^(-2)` . At the distance of 40 cm, the magnetic field will be .........................Tesla.
Options:
(a) `1 xx10^(-2)`
(b) `2 xx10^(-2)`
(c) `8 xx10^(-2)`
(d) `16 xx10^(-2)`