Question

If in circular coil of radius `R`, current `I` is flowing and in another coil `B` of radius `2R` a current `2I` is flowing , then the raatio of the magnetic fields `B_(A) and B_(B)`, produced by them will be
A. `1`
B. `2`
C. `1//2`
D. `4`

Answer 1

Correct Answer - 1
Magnetic field at centre of circular coil `A` is
`B_(A) =(mu_(0)Ni)/(2R)`
`R` is radius and I is current flowing in coil
Similarly `B_(B) =mu_(0N(2i))/(2.(2R))`
`=(mu_0Ni)/(2R) = (B_(A))/(B_(B)) =1` .