The B/H characteristics can be determined using _______

Question

Examoogle · Accepted Answer

Fluxmeter

Explanation: The B/H characteristic (or magnetization curve) of a magnetic material describes the relationship between the magnetic flux density ($B$) and the magnetic field strength ($H$). A fluxmeter is specifically designed to measure the change in magnetic flux linkage in a search coil, making it the standard instrument for plotting the hysteresis loop.

Working Principle: The fluxmeter acts as a ballistic galvanometer with negligible control torque. When the magnetic field strength $H$ in a specimen is varied, the induced EMF in a search coil wound around the specimen causes a current to flow. The fluxmeter integrates this current, and its deflection is directly proportional to the total change in flux $\Phi$ passing through the coil, allowing for the mapping of $B$ vs $H$.

Key Formulas: $B = \frac{\Phi}{A}$ — Magnetic flux density ($Wb/m^2$); $H = \frac{NI}{l}$ — Magnetic field strength ($AT/m$); $\Phi = \int e dt$ — Flux measurement principle

Key Points: A fluxmeter is an integrating device used to measure magnetic flux change.; Unlike a ballistic galvanometer, a fluxmeter does not require a correction for the period of oscillation.; The B/H curve displays non-linear behavior due to magnetic saturation.; The area of the B-H loop represents energy loss per cycle (hysteresis loss).

Advantages: High accuracy for flux measurement; Independent of the time taken for flux change

Disadvantages: Requires careful calibration; Sensitive to mechanical vibrations

Applications: Testing of transformer core materials; Determination of permanent magnet properties; Quality control in metallurgical magnetic alloys

Additional Info: Option A (Ammeter) measures current, not flux. Option C (Voltmeter) measures potential difference. Option D (Multimeter) is a general-purpose tool and lacks the specialized integration capability for plotting full B-H loops.

Answer: B is correct — A fluxmeter is used to measure magnetic flux and is the essential instrument for plotting B-H characteristics.

Exam Tip: Remember that a fluxmeter is essentially an integrating instrument; any question involving 'total flux change' usually points toward the use of a fluxmeter.

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