Electrical FE /EIT Exam Prep - Circuit Analysis 4: Reflection Resistance

[@nickpham4351]

Could you go through some more communications, computer networks and systems questions those seems more challenging to a lot of students thank you, my exam is on Aug 22nd, 2018

[@danielsampong6607]

A bit lost as to Zt=…before you get 2

[@danielkifle7173]

For Ideal transformer P in is equal to P out, so just calculating P1 will save you a lot of time. Plus I don’t think the final answer is 25w.

[@yohomielinda]

How did he get 2

[@danielsampong6607]

My question too

[@goatedwiththesauce3898]

My question too

[@lperalta12]

He added Rreflected=1Ω with the other Z= 0.414 + j1.414 and it resulted in 1.414+j1.414. If you convert that to polar you will get 2

[@hcyang82]

I don't see anything regarding Reflection Resistance in the NCEES handbook.

[@RCN587]

See page 364 - Zp = a^2Zs where a = N1/N2

[@DP-px2yu]

Is/Ip = Np/Ns, you assumed the secondary current was the same as the primary current

[@mohamedbedear4247]

Why the total power I^2 x R reflected not Z total

[@crestes666]

Because the question wanted Pout, which would only deal with that resistor. Not the total resistance in the circuit.

[@JL-fh4qw]

You only need Ztotal to calculate the primary current. Once you calculate the reflected resistance (a resistance that takes into account both load and transformer), you can just draw a simple circuit with Z and reflected resistor. To calculate Pout you want the power dissipated across this reflected resistor only.