# magnetic circuit question

Discussion in 'Homework Help' started by Vanush, Sep 23, 2008.

1. ### Vanush Thread Starter Active Member

Apr 19, 2008
46
0

I want to calculate the flux in each leg.. so, let's take the first leg, flux 1

I know that flux = BA..

I calculate magnetizing force H = NI/l = 500/0.14 = 3571.42

but B = u0 * ur * H = 5000*(4*pi*10^-7)*3571.42 = 22.43

but flux = BA = 22.43 * 0.004 = 0.0089 Wb

Not even close to the answer! (4.887 mWb)

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2. ### scubasteve_911 Senior Member

Dec 27, 2007
1,202
1
You should draw the electrical circuit equivalent, so that you may apply the necessary laws. In this case, it would be the current divider rule.

I will not solve the question for you, but I will give you the right steps to do it.

#1) Solve for total core reluctance, this involves finding the area of the core and the length, and using the permeability. You will have a resistor in series with two parallel resistors, hopefully you can find the total resistance. (sorry, thinking electrical)
Rcore = length / u0*ur*area
#2) Solve for total flux
Flux = F/Rcore = N*I/Rcore
#3) Apply the current (or flux) divider equation to solve for the various fluxes along the different paths

Steve