Question

two circular coils of radii 5 cm and 10 cm carry equal currents of 2A the coils have 50 and 100 turns respectively and are placed in such a way that their planes are perpendicular and the centres coinside ,find the magnetude of the magnetic field B at the common centre ??​

Answer 1

A : `8pixx10^-4T` if currents in the coils are in same sense

B : `4pixx10^-4T` if current in the coils are in opposite sense

C : zero if currents in the coils are in opposite sense

D : `8pixx10^-4` T if currents in the coils are in opposite sense

Correct Answer: A::C

Answer Text

`B_1=(mu_0N_1iI_1)/(2R_1)`  

`=((4pixx10^I-7)(50)(2))/(2(5xx10^-2))`  

`=4pixx10^-4T`  

`B_2=(mu_0N_2i_2)/(2R_2)`

`=((4pixx10^-7)(100)(2))/((2)(10xx10^-2))`  

`=4pixx10^-4T`  

When currets are in the same direction then  

`B_("net")=B_1+B_2`  

When curents are in the opposite direction, then  

`B_("net")=B_1-B_2`