3.1 Explain the term reactance with reference to an alternating current circuit - NSC Electrical Technology Electronics - Question 3 - 2024 - Paper 1
Question 3
3.1 Explain the term reactance with reference to an alternating current circuit.
Reactance is the opposition offered to the flow of alternating current by an induct... show full transcript
Worked Solution & Example Answer:3.1 Explain the term reactance with reference to an alternating current circuit - NSC Electrical Technology Electronics - Question 3 - 2024 - Paper 1
Step 1
3.1 Explain the term reactance with reference to an alternating current circuit.
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Answer
Reactance is the opposition offered to the flow of alternating current by an inductor or capacitor in an AC circuit. It is defined as the ratio of voltage to current in an alternating circuit when voltage and current are not in phase.
Step 2
3.2.1 State whether the circuit is predominantly inductive or capacitive. Motivate your answer.
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Answer
The circuit is predominantly capacitive because VC (15 V) is greater than VL (10 V).
Step 3
3.2.2 Calculate the supply voltage.
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Answer
Using the formula for the supply voltage, we have:
VT=VR2+(VC−VL)2=182+(15−10)2=18.68 V
Step 4
3.2.3 Calculate the phase angle.
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Answer
The phase angle can be calculated as follows:
Cos(θ)=VTVR;θ=Cos−1(18.6818)=15.51°
Step 5
3.2.4 Redraw and complete the phasor diagram in the ANSWER BOOK.
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Answer
(Phasor diagram to be included here)
Step 6
3.2.5 Explain why it could be assumed that the supply current is leading the supply voltage.
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Answer
The supply current (IR) and voltage across the resistance (VR) are always in phase, and since VR is leading VT, it is therefore safe to conclude that IR is also leading VT by the same angle. In a capacitive circuit, the supply current will always lead the supply voltage.
