Daily Practice Problems Alternating Current

Question 1:

The peak value of a.c. voltage on a 220V mains is:

220/
230/
220
240

Question 2:

What is the ratio of inductive and capacitive reactance in an a.c. circuit?

ω²LC
0
1
ω²L

Question 3:

Identify the wrong statement:

Eddy currents are produced in a steady magnetic field.
Eddy currents can be minimized by using laminated core
Induction furnace uses eddy current to produce heat
Power meters are working on the principle of eddy currents.

Question 4:

A coil of inductive reactance 1/3 Ω & resistance 1 Ω is connected to a 200 V, 50 Hz A.C. supply. The time lag between maximum voltage and current is

1/600 s
1/400 s
1/500 s
1/200 s

Question 5:

An inductor of reactance 1Ω and resistor of 2Ω are connected in series to the terminals of a 6V (rms) a.c. source. The power dissipated in the circuit is:

8 W
12 W
14.4 W
18 W

Question 6:

A choke coil and a bulb are connected in series to a d.c source. The bulb shines brightly. How does the brightness change when an iron core is inserted in the choke coil?

No change
Increase
Decrease
None

Question 7:

Why is the AC voltage preferred over DC voltage?

Easy stepping up and stepping down
Basic generation is AC
Both a& b
None of these

Question 8:

A 15μF capacitor is connected to a 220V, 50 Hz source. Find the capacitive reactance and the current (rms and peak) in the circuit.

151 Ω, 0.05 A
121 Ω, 0.04 A
133 Ω, 0.07 A
177 Ω, 0.08 A

Question 9:

An LCR series circuit is connected to an AC source. At resonance the applied voltage and the current flowing through the circuit will have a phase difference of:

π
π/2
π/4
0

Question 10:

A transformer is used:

To transform electric energy into mechanical energy.
To obtain suitable DC voltage
To transform AC into DC
To obtain suitable AC voltage

Question 11:

A power transmission line feeds input power at 2200 V to a step-down transformer with its primary windings having 3000 turns. Find the number of turns in the secondary to get the power output at 220 V.

Question 12:

An inductor 200 mH, capacitor 500 μF, resistor 10Ω are connected in series with a 100 V, variable frequency a.c source. Calculate the current amplitude at resonance and Q-factor.

Question 13:

What are the reasons behind energy losses occur in non- ideal transformer? Explain.

Question 14:

At an airport, a person is made to walk through the doorway of a metal detector, for security reasons. If she/he is carrying anything made of metal, the metal detector emits a sound. On what principle does this detector work?

Question 15:

Define the term wattles current.

Question 16:

A sinusoidal voltage of peak value 283 V and frequency 50 Hz is applied to a series LCR circuit in which R = 3 Ω, L = 25.48 mH, and C = 796 µF. Find

(a) the impedance of the circuit;

(b) the phase difference between the voltage across the source and the current;

Question 17:

For circuits used for transporting electric power, a low power factor implies large power loss in transmission. Explain.

Question 18:

A step-up transformer operates on a 230 V line and a load current of 2 A. the ratio of the primary and secondary windings is 1:25. The current in the primary.

Question 19:

A coil of inductive reactance 31 Ω has a resistance of 8Ω. It is placed in series with a condenser of capacitive reactance 25 Ω. The combination is connected to an AC source of 110 V. calculate the power factor of the circuit?

Question 20:

The reactance of a capacitor of capacitance C is X. If both the frequency and capacitance be doubled, then what is the new reactance?

**********

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In summary, problem-solving after learning a theoretical concept on CBSE Alternating Current Class 12 Physics is an essential part of the learning process. It enhances your understanding, critical thinking abilities, and retention of knowledge. Moreover, it equips you with valuable skills that are applicable in academic, personal, and professional contexts.

You must have heard of the phrase “Practice makes a man perfect”. Well, not just a man, practice indeed enhances perfection of every individual.

Practicing questions plays a pivotal role in achieving excellence in exams. Just as the adage goes, "Practice makes perfect," dedicating time to solve a diverse range of exam-related questions yields manifold benefits. Firstly, practicing questions allows students to familiarize themselves with the exam format and types of problems they might encounter. This familiarity instills confidence, reducing anxiety and improving performance on the actual exam day. Secondly, continuous practice sharpens problem-solving skills and enhances critical thinking, enabling students to approach complex problems with clarity and efficiency. Thirdly, it aids in identifying weak areas, allowing students to focus their efforts on improving specific topics. Moreover, practice aids in memory retention, as active engagement with the material reinforces learning. Regular practice also hones time management skills, ensuring that students can allocate appropriate time to each question during the exam. Overall, practicing questions not only boosts exam performance but also instills a deeper understanding of the subject matter, fostering a holistic and effective learning experience.

All About Daily Practice Problems on Class 12 Physics Alternating Current NCERT Chapter 7

Our Daily Practice Problems (DPPs) offer a diverse range of question types, including Multiple Choice Questions (MCQs) as well as short and long answer types. These questions are categorized into Easy, Moderate, and Difficult levels, allowing students to gradually progress and challenge themselves accordingly. Additionally, comprehensive solutions are provided for each question, available for download in PDF format - Download pdf solutions as well as Download pdf Questions. This approach fosters a holistic learning experience, catering to different learning styles, promoting self-assessment, and improving problem-solving skills. With our well-structured DPPs, students can excel in exams while gaining a deeper understanding of the subject matter. Hope you found the content on Class 12 Physics Alternating Current NCERT Chapter 7 useful.

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