Reducing the magnetic field to 71% of its previous value changes the magnetic energy density in the field to ________% of its original value.
A) 39
B) 50
C) 71
D) 85
E) 15

Question

Quizplus · Accepted Answer

The magnetic energy density in a field is proportional to the square of the magnetic field strength. Therefore, if the magnetic field is reduced to 71% of its previous value, the magnetic energy density will be (0.71)^2 = 0.5041 or 50.41% of its original value, which can be rounded to 50%.

Reducing the Magnetic Field to 71% of Its Previous Value