Q. A capacitor in an AC circuit has a capacitive reactance of 50 ohms. If the frequency of the AC source is increased, what happens to the capacitive reactance?
A.
Increases
B.
Decreases
C.
Remains the same
D.
Becomes infinite
Solution
Capacitive reactance (X_C) is given by X_C = 1/(2πfC). If the frequency (f) increases, X_C decreases.
Q. A capacitor in an AC circuit has a capacitive reactance of 50 ohms. What is the frequency if the capacitance is 10 microfarads?
A.
1 kHz
B.
10 kHz
C.
100 Hz
D.
1000 Hz
Solution
Capacitive reactance (X_C) is given by X_C = 1 / (2πfC). Rearranging gives f = 1 / (2πX_CC). Substituting X_C = 50 ohms and C = 10 x 10^-6 F gives f = 318.31 Hz, approximately 1 kHz.
Q. In a series RLC circuit, if the resistance is increased, what happens to the bandwidth of the resonance?
A.
Increases
B.
Decreases
C.
Remains the same
D.
Becomes zero
Solution
Increasing the resistance in a series RLC circuit decreases the bandwidth of the resonance because the quality factor (Q) is inversely proportional to resistance.
Q. In a series RLC circuit, what happens to the total impedance at resonance?
A.
It is minimum
B.
It is maximum
C.
It is equal to R
D.
It is equal to XL + XC
Solution
At resonance in a series RLC circuit, the total impedance (Z) is equal to the resistance (R) because the inductive and capacitive reactances cancel each other out.
Q. In an RLC series circuit, if the resistance is increased while keeping the inductance and capacitance constant, what happens to the quality factor (Q)?
A.
Increases
B.
Decreases
C.
Remains the same
D.
Becomes zero
Solution
The quality factor (Q) is given by Q = (1/R)√(L/C). Increasing R decreases Q.
Understanding Alternating Current (AC) is crucial for students preparing for school and competitive exams. This topic not only forms a significant part of the physics curriculum but also features prominently in various objective questions and MCQs. Practicing Alternating Current MCQ questions helps students enhance their concept clarity and boosts their confidence, leading to better exam performance.
What You Will Practise Here
Definition and characteristics of Alternating Current
Comparison between Alternating Current and Direct Current
Key formulas related to AC, including RMS and peak values
Phase difference and its significance in AC circuits
Diagrams illustrating AC waveforms and their properties
Applications of Alternating Current in daily life
Important questions on AC circuit analysis and impedance
Exam Relevance
The topic of Alternating Current is frequently tested in CBSE, State Boards, NEET, and JEE exams. Students can expect questions that assess their understanding of AC theory, calculations involving AC circuits, and real-world applications. Common question patterns include numerical problems, conceptual questions, and diagram-based queries, making it essential to practice thoroughly.
Common Mistakes Students Make
Confusing RMS value with peak value in AC calculations
Misunderstanding the phase relationship between voltage and current
Overlooking the significance of frequency in AC circuits
Neglecting to apply the correct formulas during problem-solving
FAQs
Question: What is the difference between AC and DC? Answer: Alternating Current (AC) changes direction periodically, while Direct Current (DC) flows in one direction only.
Question: How is the RMS value of AC calculated? Answer: The RMS value of an AC waveform is calculated by taking the square root of the average of the squares of the instantaneous values over one complete cycle.
Now is the time to strengthen your understanding of Alternating Current. Dive into our practice MCQs and test your knowledge to excel in your exams!
Soulshift Feedback×
On a scale of 0–10, how likely are you to recommend
The Soulshift Academy?
