B-H curve is a plot of:

Explanation:

B-H Curve

Definition: The B-H curve, also known as the magnetization curve, is a graphical representation of the relationship between magnetic flux density (B) and magnetic field strength (H) for a given material. This curve is crucial in understanding the magnetic properties of materials, particularly ferromagnetic materials, and is widely used in electrical engineering and material science.

Working Principle: The B-H curve is obtained by plotting the magnetic flux density (B) against the magnetic field strength (H) while the material is subjected to an external magnetic field. The shape of the B-H curve reveals important information about the material's magnetic behavior, including its permeability, saturation, hysteresis, and coercivity.

The B-H curve typically shows a nonlinear relationship between B and H. At low values of H, the curve is linear, indicating that the material is unsaturated and the magnetic domains are aligning with the external field. As H increases, the curve starts to bend and eventually reaches a point where further increases in H result in very little increase in B, indicating magnetic saturation. When the external magnetic field is reduced to zero, the material retains some magnetization, known as remanence. To demagnetize the material, a reverse magnetic field must be applied, known as the coercive field.

Correct Option Analysis:

The correct option is:

Option 2: Magnetic flux density and ampere turns/min.

This option correctly describes the parameters plotted on the B-H curve. Magnetic flux density (B) is measured in teslas (T) or gauss (G), and magnetic field strength (H) is measured in ampere-turns per meter (A/m) or oersteds (Oe). The B-H curve is a plot of B versus H, illustrating the material's response to the applied magnetic field.

Additional Information

To further understand the analysis, let’s evaluate the other options:

Option 1: Voltage and current.

This option is incorrect because the B-H curve does not represent the relationship between voltage and current. Voltage and current are electrical quantities, whereas the B-H curve deals with magnetic quantities. The relationship between voltage and current is typically depicted using V-I characteristics or Ohm's law.

Option 3: Current and magnetic flux.

This option is also incorrect. Although magnetic flux (Φ) and current (I) are related in electromagnetic systems, the B-H curve specifically plots magnetic flux density (B) against magnetic field strength (H), not current and magnetic flux. Current and magnetic flux relationships are better represented in the context of electromagnetic induction and Faraday's law.

Option 4: MMF and reluctance.

This option is incorrect because the B-H curve does not directly plot magnetomotive force (MMF) and reluctance. MMF, measured in ampere-turns (At), is the driving force that creates a magnetic field, while reluctance is a measure of the opposition to the magnetic flux. The B-H curve focuses on the relationship between magnetic flux density and magnetic field strength, not MMF and reluctance.

Conclusion:

Understanding the B-H curve is fundamental in the study of magnetic materials and their behavior under the influence of an external magnetic field. The correct representation of the B-H curve involves plotting magnetic flux density (B) against magnetic field strength (H). This curve provides valuable insights into the magnetic properties of materials, including their permeability, saturation, hysteresis, and coercivity. The analysis of other options helps to clarify that the B-H curve is specifically concerned with magnetic parameters rather than electrical quantities or different magnetic relationships.