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Alternating Current - ISC Class 12 Physics Questions with Answers

52 past-paper questions on Alternating Current from ISC Class 12 Physics papers (2027-2018), newest first. Open one to see its answer.

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An ac generator generating an emf $e = 300 \sin(100\pi t)\text{V}$ is connected to a $100\,\Omega$ resistor. Draw a labelled… 2027 · 5 marks · Long answer
Answer the following questions: The graph below shows variation of current (I) flowing through an electrical device with time… 2027 · 5 marks · Long answer
Answer the following questions: A train is moving on horizontal tracks 1.2m apart with a constant velocity of 36 km/hr. Vertical… 2026 · 5 marks · Long answer
Three students, X, Y and Z performed an experiment for studying the variation of A.C. with frequency in a series LCR circuit and… 2026 · 5 marks · Short answer
Answer the following questions: The continuous graph below shows variation of emf versus time when applied to a component X. The… 2026 · 5 marks · Long answer
Answer the following questions: A $70\Omega$ resistor is connected to an ac source generating an emf 'e' given by… 2026 · 5 marks · Long answer
When a coil is connected to a 200V dc supply, the current flowing through it is found to be 1A. However, when it is connected to… 2026 · 5 marks · Long answer
Answer the following questions: Define the co-efficient of self-inductance. (Recall) (1) Consider an A.C. source of frequency… 2026 · 5 marks · Numerical
Explain why the efficiency of a transformer is always less than 100%. 2026 · 1 mark · Short answer
Sketch a labelled graph showing variation of impedance Z of a series LCR circuit with the frequency f of an ac supply. Mark the… 2026 · 2 marks · Drawing
Power Corporation of India wanted to transmit power of 11 kW from tower 1 to tower 2 at 220 V or 22000 V. Which of the two… 2025 · 3 marks · Short answer
Explain why core of a transformer is always laminated. 2025 · 1 mark · Short answer
A student was given a frequency generator, a source, an inductor, a capacitor, a resistor and an ammeter. After connecting the… 2025 · 3 marks · Long answer
Three students, X, Y and Z performed an experiment for studying the variation of a.c. with frequency in a series LCR circuit and… 2025 · 5 marks · Short answer
Consider an alternating current (a.c.) source whose angular frequency ($\omega$) changes constantly but has a fixed peak voltage… 2025 · 1 mark · MCQ
Figure 3 below shows an ideal transformer. Explain why current flowing through secondary coil is greater than that in primary… 2025 · 1 mark · Short answer
An alternating current (a.c.) voltage source at 50 Hz is applied to a series combination of resistor A of resistance ‘P' and… 2025 · 1 mark · MCQ
An inductor-resistor circuit (LR) series circuit connected to an alternating current (a.c.) source of 220 V, 50 Hz, the resistor… 2025 · 2 marks · Numerical
An alternating emf $E = 5.0 \sin(314t)\text{ V}$ is applied to a circuit containing a resistor connected in series with an… 2025 · 5 marks · Numerical
The graph here shows a variation of $I_{rms}$ with angular frequency ‘$\omega$’ for two different LCR circuits. Which of the two… 2025 · 2 marks · Short answer
In an inductance-capacitance-resistance (LCR) series circuit, which is connected to an alternating current (a.c.) source of a… 2025 · 3 marks · Long answer
Give the expression for the power factor in an LR circuit in terms of the resistance ‘R’ and inductive reactance ‘$X_L$’. 2025 · 1 mark · Short answer
An arc lamp takes 10 A at 50 V. Calculate the impedance of a choke of 1-ohm resistance to be connected in series with an arc lamp… 2025 · 3 marks · Numerical
When current flowing through a solenoid increases from $0$ to $10\text{ A}$ in $0.2\text{ s}$, an emf of $20\text{ V}$ is induced… 2025 · 5 marks · Short answer
A choke coil has a self-inductance of $0.5\text{ H}$ and a resistance of $50\ \Omega$. It is connected to a $220\text{ V}$… 2025 · 5 marks · Numerical
The graphs shown below are for three different Inductance, Capacitance, and Resistance (LCR) circuits (1), (2), and (3). Identify… 2025 · 1 mark · MCQ
Match the following conditions for an LCR series circuit with the corresponding phase relation between current and voltage: 2025 · 3 marks · Match
A $220\text{ V}$, $50\text{ Hz}$ ac source is connected to a coil having coefficient of self-inductance of $1\text{ H}$ and a… 2024 · 5 marks · Short answer
What type of transformer is used in a mobile phone charger? Why is the core of a transformer made of soft iron and not of steel? 2024 · 2 marks · Short answer
An ac generator generates an emf which is given by $e = 311\sin(240\pi t)\text{ V}$. Calculate: (1) frequency of the emf. (2)… 2023 · 5 marks · Numerical
An $80\\,\Omega$ resistor, a $1\cdot0\text{ H}$ inductor and a $40\\,\mu\text{F}$ capacitor are connected in series to an a.c… 2023 · 5 marks · Numerical
A $60\,\Omega$ resistor, a $1\cdot0\text{ H}$ inductor and a $4\mu\text{F}$ capacitor are connected in series to an ac supply… 2023 · 5 marks · Numerical
Give any one reason why efficiency of a transformer is always less than 1. 2023 · 1 mark · Short answer
An A.C. generator generating an e.m.f of $\varepsilon = 300 \sin (100\pi) t$ is connected to a series combination of… 2022 · 1 mark · MCQ
A $2\ \mu\text{F}$ capacitor, $100\ \Omega$ resistor and $8\text{ H}$ inductor are connected in series with an ac source. At a… 2022 · 3 marks · Short answer
Which of the following is not the characteristic of resonance in an LCR series circuit? 2022 · 1 mark · MCQ
An alternating e.m.f of 100V is applied to a circuit containing a resistance of $40\ \Omega$ and an inductance L in series. The… 2022 · 4 marks · Short answer
The loss of power in a transformer can be reduced by: 2022 · 1 mark · MCQ
Figure 10 given below shows a graph of emf ‘ε’ generated by an ac generator verses time. What is the frequency of the emf? 2022 · 1 mark · MCQ
The teacher of Priti's school took the students on a study trip to a power generating station, located nearly 250 km away from… 2022 · 4 marks · Short answer
A graph showing variation in impedance Z of a series LCR circuit, with frequency f of alternating emf applied to it is shown… 2022 · 1 mark · MCQ
A $400\ \Omega$ resistor, a $3\text{ H}$ inductor and a $5\ \mu\text{F}$ capacitor are connected in series to a… 2020 · 5 marks · Short answer
When an alternating emf $e = 310 \sin(100\pi t)\text{ V}$ is applied to a series LCR circuit, current flowing through it is… 2020 · 5 marks · Short answer
An a.c. source of emf $\varepsilon = 200 \sin \omega t$ is connected to a resistor of $50\\ \Omega$. Calculate: (1) Average… 2019 · 5 marks · Short answer
What is the value of power factor for a pure resistor connected to an alternating current source? 2019 · 1 mark · Short answer
A transformer is used to step up an alternating emf of $200\text{ V}$ to $440\text{ V}$. If the primary coil has $1000$ turns… 2019 · 2 marks · Numerical
An alternating emf of $200\text{ V}$, $50\text{ Hz}$ is applied to an L-R circuit, having a resistance $R$ of $10\\ \Omega$ and… 2019 · 5 marks · Numerical
An $8\text{ H}$ inductor, a $2\ \mu\text{F}$ capacitor and a $100\ \Omega$ resistor are connected in series to an A.C. supply of… 2018 · 5 marks · Numerical
Name any two types of energy losses in a transformer. State how any one of them can be minimized. 2018 · 2 marks · Short answer
An alternating emf of $220\text{V}$ is applied to a circuit containing a resistor R having resistance of $160\,\Omega$ and a… 2018 · 5 marks · Numerical
An A.C. generator generating an emf of $\varepsilon = 300 \sin(100\pi t)\text{ V}$ is connected to a series combination of… 2018 · 5 marks · Numerical
An A.C. generator generating an emf ‘$E$’ given by $E = 311 \sin(100\pi t)$ is connected to a $44\ \Omega$ resistor. Calculate… 2018 · 5 marks · Numerical

Alternating Current - ISC Class 12 Physics Questions with Answers

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