The magnetic energy stored in an inductor is given by the formula: U=‌
1
2
LI2 Where: U is the energy stored, L is the inductance, I is the current through the inductor. In this case, the current increases from I1=2A to I2=3A. Calculating the initial energy stored U1 when the current is I1 : U1=‌
1
2
LI12=‌
1
2
×L×4=2L Calculating the energy stored U2 when the current is I2 : U2=‌
1
2
LI22=‌
1
2
×L×9=4.5L The increase in energy stored, ∆U, is: ∆U=U2−U1=4.5L−2L=2.5L To find the percentage increase in energy stored: Percentage Increase =‌