Amateur ExtraE5B03

How is impedance in polar form converted to an equivalent admittance?

B
Answer
Electrical principles and calculations
Type
A
Take the reciprocal of the angle and change the sign of the magnitude
B
Take the reciprocal of the magnitude and change the sign of the angle
C
Take the square root of the magnitude and add 180 degrees to the angle
D
Square the magnitude and subtract 90 degrees from the angle

Answer Notes

Admittance (Y) is the mathematical reciprocal of impedance (Z). When working with complex numbers in polar form, an impedance is written as a magnitude (Z) and an angle (θ). To find the reciprocal of a number in polar form, you divide 1 by the magnitude (1/Z) and subtract the original angle from zero (0 - θ), which simply changes its sign. Therefore, the equivalent admittance has a magnitude of 1/Z and an angle of -θ. Common distractors suggest taking the reciprocal of the angle or changing the sign of the magnitude. These operations are mathematically incorrect for complex numbers; a magnitude must always remain a positive distance from the origin.
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What letter is commonly used to represent susceptance?
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