A current of 10 A flow around a closed path in a circuit which is in the horizontal plane as shown in the figure. The circuit consists of eight alternative arcs of radii `r_(1)=0.08m` and `r_(2)=0.12m` . Each subtends the same angle at the centre. If magnetic field at centre produced by this circuit is `etaxx10^(-5)T`, then the value of `eta` is ?

Answer

6.54

Explanation

The smaller and bigger arcs combined together constitute half circle each.
`B=(mu_(0)I)/(4R_(1))+(mu_(0)I)/(4R_(2))=(mu_(0)i)/4[1/(R_(1))+1/(R_(2))]=(4pixx10^(-7)xx10)/4xx[1/0.08+1/0.12]=314/48xx10^(-5)=6.54xx10^(-5)T`