A long straight wire with a circular crosssection having radius $R$, is carrying a steady current $I$. The current I is uniformly distributed across this cross-section. Then the variation of magnetic field due to current I with distance $r\;( r < R )$ from its centre will be
  • A$B \propto r^{2}$
  • B$B \propto r$
  • C$B \propto \frac{1}{ r ^{2}}$
  • D$B \propto \frac{1}{r}$
JEE MAIN 2022, Easy
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