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jaus tail
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Homework Statement
A function is given as W = ln (Z)
Z = x + i y
W = u + i v
i is sqrt of (-1)
The u = constant lines get mapped in z plane as ?
Homework Equations
Z = x + i y = [ sqrt {x2 + y2 } ] ei (theta)
where theta is tan-1 (y/x)
The Attempt at a Solution
Function w is
w = ln (z)
= ln( sqrt {[x2 + y2 ] } multiply with ei (theta)
Now ln (a b) = ln (a) + ln (b)
so w = ln (sqrt [x2 + y2 ]) + i(theta) ln (e)
The first part is real, while second part is imaginary.
w = u + iv.
So u = ln(sqrt [x2 + y2 ] )
Question says u = constant lines get mapped in z plane as ?
u = constant
so ln (sqrt (x2 + y2 ) = constant.
Now how to proceed? In answer they've said concentric circles with radius ec.
I got till u = ln (sqrt (x2 + y2)
remove sqrt out as 1/2 we get:
u = 1/2 ( ln (x2 + y2) )
equation of circle is x2 + y2 = constant.
But there is log in u.