When 100 V dc is applied across a solenoid, a current of 1 A flows in it. When 100 V ac is applied across the same solenoid the current drops to 0.5 A. If the frequency of the ac source is 50 Hz, the impedance and inductance of the solenoid are:
1
200 and 0.55 H
2
100 and 0.86 H
3
200 and 1.0 H
4
100 and 0.93 H
Official Solution
Correct Option:
(1)
For the DC case, the impedance is simply the resistance , and the current is given by: For the AC case, the total impedance is the sum of the resistance and the inductive reactance : The impedance for an inductive circuit is given by:
Substitute the values: The inductive reactance is related to the inductance by:
Substitute the frequency :
02
PYQ 2023
medium
physicsID: cuet-ug-
Find the effective impedance in the circuit if the source is:a) DC source and b) High frequency AC source
1
For DC, and for AC,
2
For DC, and for AC,
3
For DC, and for AC,
4
For DC, and for AC,
Official Solution
Correct Option:
(2)
For DC, the inductors act as short circuits (because their reactance is zero) and the capacitors act as open circuits (because their reactance is infinite). Therefore, the impedance for a DC source is simply . For high-frequency AC, the inductors act as high-impedance elements, and the capacitors act as low-impedance elements. Therefore, the impedance for a high-frequency AC source is , as the inductors contribute effectively to the impedance while the capacitors' reactance approaches zero.
03
PYQ 2023
medium
physicsID: cuet-ug-
In AC circuits, the relation that holds is , where:
1
in case of a.c. circuit containing R and L in series
2
in case of a.c. circuit containing R and C in series
3
in case of a.c. circuit containing L and C in series
4
in case of a.c. circuit containing R, L, and C in series
Official Solution
Correct Option:
(2)
In AC circuits, the impedance is calculated depending on whether the components are resistors, inductors, or capacitors:
- For a circuit containing a resistor and an inductor in series, the impedance is:
- For a circuit containing a resistor and a capacitor in series, the impedance is:
- For a circuit containing only an inductor and a capacitor in series, the impedance is:
Thus, the correct answer is A, B, and C only.
About Impedance - CUET-UG
Impedance is a vital chapter for CUET-UG aspirants. Mastering the concepts covered in this chapter is essential for securing a top rank.
By rigorously practicing the previous year questions associated with this chapter, you can identify high-yield topics, understand the examiner's perspective, and boost your confidence during the actual exam.
Frequently Asked Questions
Why focus on Impedance PYQs?
Analyzing PYQs for this specific chapter reveals the most frequently tested concepts and the typical complexity of questions, allowing you to tailor your study plan efficiently.
How to best use this analysis?
Review the topic breakdown to see which sub-topics within Impedance carry the most weight. Then, tackle the questions iteratively to solidify your understanding.
