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    • Thread Starter

    I know this'll seem really obvious to most of you, but I've never studied 'inductance' so have no idea where to even start :p:

    'The current in a coil changes from 5A to 2A in 0.05 seconds and induces a voltage of 30V in the coil, the inductance of the coil is?
    a) 0.2H
    b) 0.5H
    c) 1.5H
    d) 2.0H

    (I don't even know what H is )
    Thank-you m'dears!

    EMF = inductance x rate of change of current

    dI/dt = 3/0.05 = 60

    so L = 30 / 60 = 0.5H

    I've almost passed my level 2 c&g tech cert now, but i'm trying to get ahead of the game, if i remember correctly H is (Henry) which is a measure of the inductance of a coil.
    I just got this question on a Mock exam and i worked it out like this:

    Inductance (L) =
    Current change, in this instance (5A-2A) / Rate of change in seconds (0.05s)
    3A/0.05s = 60
    30v/ 60 = 0.5 Henry
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