Which statement about magnetic reluctance is true?

Which statement about magnetic reluctance is true?

• A. It decreases with longer path length and increases with larger cross-sectional area.
• B. It increases with longer path length and decreases with larger cross-sectional area.
• C. It increases with larger μ.
• D. It is independent of geometry.

Answer: (B)

Magnetic reluctance acts like the resistance to magnetic flux, and it depends on how long the magnetic path is, how large the cross-sectional area is, and how permeable the material is. The reluctance is given by R = l / (μ A). So, if the path length l increases, reluctance increases; if the cross-sectional area A increases, reluctance decreases; and if the material has higher permeability μ, reluctance decreases as well. That’s why the statement describing reluctance as increasing with longer path length and decreasing with larger cross-sectional area is the correct one. It aligns with the l/(μA) relationship. Options claiming the opposite effects, or that reluctance grows with larger μ, or that geometry doesn’t matter, don’t fit the formula and the physical behavior of magnetic circuits.

Magnetic reluctance acts like the resistance to magnetic flux, and it depends on how long the magnetic path is, how large the cross-sectional area is, and how permeable the material is. The reluctance is given by R = l / (μ A). So, if the path length l increases, reluctance increases; if the cross-sectional area A increases, reluctance decreases; and if the material has higher permeability μ, reluctance decreases as well.

That’s why the statement describing reluctance as increasing with longer path length and decreasing with larger cross-sectional area is the correct one. It aligns with the l/(μA) relationship. Options claiming the opposite effects, or that reluctance grows with larger μ, or that geometry doesn’t matter, don’t fit the formula and the physical behavior of magnetic circuits.