# Problem with Robert E.Collin equation in his book

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#### amirmg

##### Newbie level 3 Robert E.Collin

Dear Users
Can anyone tell me why didn't Mr.Collin written {cdz d[V(z+dz,t)]/dt } on the page 74 equation (3.1b) of foundation for microwave engineering second edition.
he has written {cdz d[V(z,t)]/dt }.The voltage on the capacitor is v(z+dz,t) not v(z,t).

#### alard

##### Member level 4 Re: Robert E.Collin

this is because V(z+dz,t)]/dt has already been presented by V(z,t)]/dt on the top of P74. So do I(z+dz,t)]/dt

#### amirmg

##### Newbie level 3 Re: Robert E.Collin

come on man there have been written V(z+dz,t)=V(z,t)+d[V(z,t)/dz]dz
what happened for the second term ?

#### alard

##### Member level 4 Re: Robert E.Collin

Sorry, I don't quite understand you.

You question should be why dV(z+dz,t)/dt=dV(z,t)/dt.
I think it is because the differential is to t not z, and take the limit dz to 0.

#### amirmg

##### Newbie level 3 Re: Robert E.Collin

yea,I asked how can we assume V(z+dz,t)=V(z,t) ,what about the voltage on the inductor ? ad I mainly interested to know when we derivate the term

d/dt{V(z+dz,t)}=d/dt{ V(z,t) + d [v(z,t) /dz ] dz }

==> d (V(t,z) )dt + [d2 V(z,t) /dzdt ]dz

how we vanish the red term ???

amir

#### ng wei

##### Member level 3 Re: Robert E.Collin

does anybody have the solution manual of the book Foundations of microwave engineering by robert collin ---- 2nd edition

#### khansuleman77

##### Newbie level 1 Re: Robert E.Collin

dear did u find the solution manual for the book " foundation of microwave engineering by robert e collin"

kindly if u have.. plz help me

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