AIIMS 2016 · Physics · Magnetic Effects of Current
The magnetic field at the centre O of the arc shown in the figure is
The magnetic field at the centre O of the arc shown in the figure is
Options
A2I(2+π)×r10−7
B2I(2+4π)×r10−7
CI(2+π)×r10−7
DI(2+4π)×r10−7
Correct answer
B. 2I(2+4π)×r10−7
Step-by-step solution
Here, a=2r
Magnetic field at point O due to AB is
B1=4πμ0aI=4π(r/2)μ0I
Magnetic field at point O due to BCD is
B2=4πrμ0I\left(\frac{\pi}{2}\right)MagneticfieldatpointOduetoD EisB_3=\frac{\mu_0 I}{4 \pi a}=\frac{\mu_0 I}{4 \pi(r / \sqrt{2})}ResultantmagneticfieldatpointOisB=B1+B2+B3=4π(r/2)μ0I+4πrμ0I(2π)+4π(r/2)μ0I=4πrμ0I(2+2π+2)=4πrμ0I(22+2π)=4πrμ0II(2+4π)=r10−7×2I(2+4π)[∵4πμ0=10−7]$