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Phasors for Resistors quiz

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  • What does it mean for voltage and current to be 'in phase' across a resistor in an AC circuit?
    It means that both voltage and current have the same angle (omega t) at any time, so their phasors line up perfectly.
  • What is the general equation for the angle of a phasor in an AC circuit?
    The angle for any phasor is given by omega t, where omega is the angular frequency and t is time.
  • If the angular frequency is 20 s⁻¹ and the circuit is closed for 0.2 seconds, what is the phasor angle?
    The angle is omega times t, so 20 × 0.2 = 4 radians.
  • How many degrees is 4 radians approximately equal to?
    4 radians is approximately 229 degrees.
  • In which quadrant does a phasor at 229 degrees lie?
    A phasor at 229 degrees lies in the third quadrant.
  • When drawing phasors for voltage and current across a resistor, how should they be oriented?
    They should be lined up at the same angle, since they are in phase.
  • What happens to the voltage and current phasors as they rotate over time in a resistor?
    They remain lined up and always point in the same direction because they are in phase.
  • What is the key takeaway about voltage and current in resistors in AC circuits?
    The voltage across the resistor is always in phase with the current through the resistor.
  • What does 'omega' represent in the context of phasors?
    'Omega' represents the angular frequency of the AC source.
  • If you choose a different time to measure the phasors, what must remain the same for voltage and current?
    Their angles must still match, so they remain in phase.
  • What is the significance of the circuit being 'broken' before closing in the example?
    When the circuit is broken, nothing happens; time starts counting once the circuit is closed.
  • Does the color used to draw phasors on a diagram affect their meaning?
    No, the color does not matter as long as the angles are correct.
  • What mathematical operation do you use to find the phasor angle from angular frequency and time?
    You multiply the angular frequency (omega) by the time (t).
  • Why is it important to remember that voltage and current are in phase for resistors?
    Because it helps in analyzing and drawing phasor diagrams for AC circuits with resistors.
  • Can you draw the voltage and current phasors at any angle as long as they match?
    Yes, as long as both phasors are at the same angle, they are in phase regardless of the specific value.