Version 7


    This is a 25-question quiz focusing on information regarding various aspects of inductors, including theory, magnetic materials, characteristics, and specifications of SMD power inductors.


    1) _________ states that when a time-varying current I(t) flows in a conductor, a magnetic field H(t) is induced in the conductor.


    2) Planar inductors have magnetic cores mounted above and below the plane of a printed circuit board (PCB). Which of the following is NOT an advantage of a planar inductor?


    3) Magnetic cores are __________ to reduce eddy current losses.


    4) True or False: Magnetic shielded power inductors are recommended for EMC-critical applications. The shielding prevents uncontrolled magnetic coupling of the windings with adjacent conductor tracks or components.


    5) Inductance can be highly variable once ________ occurs.


    6) The inductor is to the __________ field what the capacitor is to the ________ field. The _________ rating is to the capacitor what the ________ rating is to the inductor. The _________ material in a capacitor is to the electric field what ___________ material in an inductor is to the magnetic field.


    7) Soft magnetic materials can achieve a high value of flux density in the presence of a relatively low value of magnetic field intensity. Hence, they can be easily magnetized and demagnetized. From the list below, which is NOT a soft magnetic material?


    8) True or False: The self-heating results from the power losses in relation to the component’s ability to dissipate heat. Self-heating of an inductor coil is the ohmic loss caused by the D.C. resistance of the wire.


    9) A(n) ______ inductor or choke has a stepped air gap.


    10) True or False: Compared to a magnetic core without an air gap, a magnetic core with an air gap can store more energy, is less susceptible to variations in the magnetic properties of the core, and saturates at higher values of current.


    11) Which graph is the B-H curve of a hard magnetic material?


    True or False: Chip bead ferrites are often positioned at the inputs and outputs of switching regulators to filter high frequency noise.


    13) True or False: When designing an inductor, a typical assumption is that the core or iron loss is often negligible compared to winding loss.


    14) True or False: Ferrite materials have high permeability, offering an easy path for magnetic flux (low reluctance). This characteristic helps contain the flux within the inductor’s core, which in turn enables the construction of inductors with low values and large size.


    15) Faraday's law says that an EMF will be induced in a magnetic circuit as long as the flux is changing. The ______ of the induced EMF is equal to the time rate of the change of flux linkage of the circuit.


    16) What is the saturation current of a 47uH WE-PD Series inductor?


    17) __________ says that when a steady electric current passes through a wire it creates a magnetic field around the conductor.


    18) True or False: Lenz's law says that the induced EMF due to changing flux is always in a direction such that the current it produces tends to oppose the changing flux that is causing the current.


    19) The fringing effect in an air gapped core causes the overall inductance to ___________ because the reluctance of the air gap is ____________.


    20) What's the total inductance of the following circuit:


    21) What is the approximate temperature rise of a WE-PDF 6.2µH power SMD shielded inductor at 4A?


    22) What is the RMS current of a 3.3µH WE-PD Series Power Inductor?


    23) Reluctance is the effect of a magnetic circuit retarding the flow of the magnetic field. What is the inverse of reluctance?


    24) At high frequencies, the skin depth phenomenon causes current in a conductor to cluster near the surface of a conductor due to the AC magnetic field created by the conductor current. This is a manifestation of _________ Law whereby current flows inside a conductor to oppose the AC flux in the form of eddy currents.


    25) What is the maximum DC resistance of a WE-HCI 10 µH 15A (Irms) SMD High Current Inductor?

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