E5C12
ELECTRICAL PRINCIPLES · Coordinate systems and phasors in electronics: rectangular coordinates; polar coordinates; phasors; logarithmic axes
E5C12E5C →
Which point on Figure E5-1 best represents the impedance of a series circuit consisting of a 300-ohm resistor and a 19-picofarad capacitor at 21.200 MHz?
- APoint 1
- BPoint 3
- CPoint 7
- DPoint 8
Why For a series RC circuit the impedance is Z = R - jXc, with Xc = 1/(2*pi*f*C). Here Xc = 1/(2*pi*21.2e6*19e-12) = about 395 ohms, so Z is approximately 300 - j395 ohms. On the rectangular graph that means going right 300 units on the resistance axis and down about 400 units on the reactance axis, which is where Point 1 falls.
Watch out The point at 300 + j400 is the mirror image above the real axis, which would be a 300-ohm resistor in series with an inductor, not a capacitor; other points swap the resistance and reactance values.
Capacitors go DOWN on the graph (negative j), inductors go UP. Read R across, X up or down.
HamSandwich explanation, first draft. The question and answers are the NCVEC text.
The rest of E5C
- E5C01 Which of the following represents pure capacitive reactance of 100 ohms in rectangular notation?
- E5C02 How are impedances described in polar coordinates?
- E5C03 Which of the following represents a pure inductive reactance in polar coordinates?
- E5C04 What type of Y-axis scale is most often used for graphs of circuit frequency response?
- E5C05 What kind of diagram is used to show the phase relationship between impedances at a given frequency?
- E5C06 What does the impedance 50 - j25 ohms represent?
- E5C07 Where is the impedance of a pure resistance plotted on rectangular coordinates?
- E5C08 What coordinate system is often used to display the phase angle of a circuit containing resistance, inductive…
- E5C09 When using rectangular coordinates to graph the impedance of a circuit, what do the axes represent?
- E5C10 Which point on Figure E5-1 best represents the impedance of a series circuit consisting of a 400-ohm resistor…
- E5C11 Which point in Figure E5-1 best represents the impedance of a series circuit consisting of a 300-ohm resistor…
- E5C12 Which point on Figure E5-1 best represents the impedance of a series circuit consisting of a 300-ohm resistor…