Hysteresis meaning: Hysteresis is not a measure of lines of force per unit area; it describes the lagging relationship between B and H in a magnetic material (the hysteresis loop). True or false?
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ATrue
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BFalse
Answer
Correct Answer: False
Explanation
Introduction / Context:This item distinguishes between magnetic flux density and hysteresis. Misdefining hysteresis leads to incorrect interpretations of core losses and material selection for magnetic components.
Given Data / Assumptions:
- Flux density B is flux per unit area (measured in tesla).
- Hysteresis describes the path-dependent relationship between B and H.
- The hysteresis loop area quantifies hysteresis loss per cycle.
Concept / Approach:
“Number of lines of force per unit area” corresponds to flux density B, not hysteresis. Hysteresis refers to the lag (history dependence) in magnetic response: when H cycles, B follows a loop due to domain dynamics, causing energy loss and residual magnetization (retentivity).
Step-by-Step Solution:
Define flux density: B = Φ / A with unit tesla.Define hysteresis: difference between magnetization curves during increasing and decreasing H, producing a closed B–H loop.Relate loop area to energy loss per unit volume per cycle.Compare the claim with these definitions; it confuses B with hysteresis, so the claim is false.Verification / Alternative check:
Observe B–H curves from material datasheets. The loop demonstrates hysteresis; separate measurements of B (tesla) concern field intensity and geometry, not hysteresis alone.
Why Other Options Are Wrong:
- Choosing “True” would redefine hysteresis incorrectly and obscure the cause of magnetic core losses and remanence.
Common Pitfalls:
Equating lines-of-force visuals with quantitative B; overlooking that hysteresis depends on material microstructure and frequency, while B depends on instantaneous field and geometry.
Final Answer:
False