Given, side of cube, a=1mm=1×10−3m Radius of circular loop, R=20cm=20×10−2m Current in loop, I=2A As we know that, magnetic field due to loop, B=‌
1
2
‌
µ0I
R
where, µ0 is free space permittivity, i.e. 4π×10−7 and magnetic energy stored, E=‌
1
2
‌
B2V
µ0
where, V= volume of cube. ‌ Therefore, ‌E‌‌=‌