(New page: =1.49 (a,b,f,i)== Express each of the following complex numbers in polar form, and plot them in the complex plane, indicating the magnitude and angle of each number. A) <math> 1 + j\sqrt...)
 
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=1.49 (a,b,f,i)==
 
 
Express each of the following complex numbers in polar form, and plot them in the complex plane, indicating the magnitude and angle of each number.  
 
Express each of the following complex numbers in polar form, and plot them in the complex plane, indicating the magnitude and angle of each number.  
  

Revision as of 08:47, 21 November 2008

Express each of the following complex numbers in polar form, and plot them in the complex plane, indicating the magnitude and angle of each number.

A) $ 1 + j\sqrt{3} $

$ r = \sqrt{1^2 + \sqrt{3}^2} = \sqrt{4} = 2 $

$ \theta = arctan(\sqrt{3}/1) = arctan(\sqrt{3}) = \frac{\pi}{3} $

Therefore the polar form of this complex number is: $ 2e^{j\frac{\pi}{3}} $

B) $ -5 $

$ r = 5 $

$ \theta = \pi $

Therefore the polar form of this complex number is: $ 5e^{j\pi} $

F) $ (1 + j)^{5} $

$ r = \sqrt{1^2 + 1^2} = \sqrt{2} $

$ \theta = \frac{\pi}{4} $

$ (1 + j) = \sqrt{2}e^{j\frac{\pi}{4}} $

$ (1 + j)^{5} = (\sqrt{2}e^{j\frac{\pi}{4}})^{5} = 2^{\frac{5}{2}}e^{j\frac{5\pi}{4}} = 4\sqrt{2}e^{j(\pi + \frac{\pi}{4})} =4\sqrt{2}e^{j\pi}e^{j\frac{\pi}{4}} = -4(\sqrt{2}e^{j\frac{\pi}{4}}) = -4(1 + j) $

Therefore the polar form of this complex number is: $ -4(\sqrt{2}e^{j\frac{\pi}{4}}) $

I) $ \frac{1 + j\sqrt{3}}{\sqrt{3} + j} $

$ r = 2 $

$ Equation 1 = 1 + j\sqrt{3} => \theta_{1} = \frac{\pi}{3} $

$ Equation 2 = \sqrt{3} + j => \theta_{2} = \frac{\pi}{6} $

$ \frac{2e^{j\frac{\pi}{3}}}{2e^{j\frac{\pi}{6}}} = \frac{e^{j\frac{\pi}{3}}}{e^{j\frac{\pi}{6}}} = e^{j(\frac{\pi}{3} - \frac{\pi}{6})} = e^{j\frac{\pi}{6}} $

Therefore the polar form of this complex number is: $ e^{j\frac{\pi}{6}} $

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Questions/answers with a recent ECE grad

Ryne Rayburn