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JEE-Main - Grade 12 - Physics - Alternating Current - Introduction and Snapshot of Alternating Current - Study ref# 824

Introduction: We have so far considered direct current (dc) sources and circuits with dc sources. These currents do not change direction with time. But voltages and currents that vary with time are very common. The electric mains suppl... read more

JEE-Main - Grade 12 - Physics - Alternating Current - Introduction and Snapshot of Alternating Current - Study ref# 825

Following section must be covered to understand the Alternating Current: 1. Introduction 2. AC Voltage Applied to a Resistor 3. Representation of AC Current and Voltage by Rotating Vectors – Phasors 4. AC Voltage Applied to an In... read more

JEE-Main - Grade 12 - Physics - Alternating Current - Target Setup for Alternating Current - Study ref# 826

Student requires to achieve the following milestones to get better grip over Alternating Current. The milestones / targets are as follows: Starting Point: Days 0Test TypeAppear on TestTarget TestsScorePractice Test000%Chapter Tes... read more

JEE-Main - Grade 12 - Chemistry - Electrochemistry - Study ref# 9742

Why is alternating current used for measuring resistance oof an electrolytic solution? Answer: Alternating current is used in electrolysis so that concentration of ions in the solution remains constant and extract value of resistance is m... read more

JEE-Main - Grade 12 - Physics - Electromagnetic Induction - Study ref# 10544

A cylindrical bar magnet is rotated about its axis in the figure. A wire is connected from the axis and is made to touch the cylindrical surface through a contact. Then (a) a direct current flows in the ammeter A. (b) no current fl... read more

JEE-Main - Grade 12 - Physics - Alternating Current - Study ref# 10562

An alternating current generator has an internal resistance Rg and an internal reactance Xg.It is used to supply power to a passive load consisting of a resistance  Rg and a reactance XL.For maximum power to be delivered from the generato... read more

JEE-Main - Grade 12 - Physics - Alternating Current - Study ref# 10563

When a voltage measuring device is connected to AC mains, the meter shows the steady input voltage of 220V. this means (a) Input voltage cannot be AC voltage, but a DC voltage. (b) Maximum input voltage is 220V. (c) The meter reads ... read more

JEE-Main - Grade 12 - Physics - Alternating Current - Study ref# 10564

To reduce the resonant frequency in an L-C-R series circuit with a generator (a) the generator frequency should be reduced. (b) another capacitor should be added in parallel to the first. (c) the iron core of the inductor should ... read more

JEE-Main - Grade 12 - Physics - Alternating Current - Study ref# 10565

Define capacitive reactance. Write its S.I. unit. Answer: It is defined as the opposition to the flow of current in ac circuits offered by a capacitor. Alternatively,   S.I. unit: oh... read more

JEE-Main - Grade 12 - Physics - Alternating Current - Study ref# 10566

State which of the two a capacitor or an inductor, tends to become SHORT when the frequency of the applied alternating voltage has a high value. Answer: The capacitor. Detailed Answer: Between inductor and capacitor, the capacitor w... read more

JEE-Main - Grade 12 - Physics - Alternating Current - Study ref# 10567

The figure shows sinusoidal curves representing oscillating supply voltage and current in an ac circuit. Draw a phasor diagram to represent the current and supply voltage appropriately as phasors. State the phase difference between th... read more

JEE-Main - Grade 12 - Physics - Alternating Current - Study ref# 10569

Show that in the free oscillations of an LC circuit, the sum of energies stored in the capacitor and the inductor is constant in time. Answer: At an instant t, charge q on the capacitor and the current i are given by: read more

JEE-Main - Grade 12 - Physics - Alternating Current - Study ref# 10570

Which of the following combinations should be selected for better tuning of an L-C-R circuit based for communication? (a)   (b) (c... read more

JEE-Main - Grade 12 - Physics - Alternating Current - Study ref# 10572

An alternating voltage is applied to the circuit containing a resistor R connected in series with a black box. The current in the circuit is found to be (i) State whether the element ... read more

JEE-Main - Grade 12 - Physics - Alternating Current - Study ref# 10573

A capacitor ‘C’, a variable resistor ‘R’ and a bulb ‘B’ are connected in series to the ac mains in circuit as shown. The bulb glows with some brightness. How will the glow of the bulb change if (i) a dielectric slab is introduced between the... read more

JEE-Main - Grade 12 - Physics - Alternating Current - Study ref# 10574

A source of ac voltage, is connected across a pure inductor of inductance L. Derive the expressions for the instantaneous current in the circuit. Show that average power dissipated in the circuit is zero. Answer: Derivation of instantaneous... read more

JEE-Main - Grade 12 - Physics - Alternating Current - Study ref# 10575

A sinusoidal voltage of peak 10 V is applied to a series LCR circuit in which resistance, capacitance and inductance have values of 10, 1and 1 H respectively. Find (i) the peak voltage across the inductor at resonance (ii) quality fact... read more

JEE-Main - Grade 12 - Physics - Alternating Current - Study ref# 10576

(i) When ac source is connected to an ideal inductor shows that the average power supplied by the source over a complete cycle is zero. (ii) A lamp is connected in series with an inductor and an ac source. What happens to the brightness o... read more

JEE-Main - Grade 12 - Physics - Alternating Current - Study ref# 10577

An inductor L of inductance XL is connected in series with a bulb B and an ac source. How would brightness of the bulb change when (i) number of turns in the inductor is reduced, (ii) an iron rod is inserted in the inductor and (iii) a capac... read more

JEE-Main - Grade 12 - Physics - Alternating Current - Study ref# 10578

A circuit containing an 80mH inductor and a 250capacitor in series connected to a 240 V, 100rad/s supply. The resistance of the circuit is negligible. (i) obtain rms value of current. (ii) What is the total average power consumed by... read more

JEE-Main - Grade 12 - Physics - Alternating Current - Study ref# 10579

An inductor of reactance 1and a resistor of 2 are connected in series to the terminals of a 6V(rms) ac source. The power dissipated in the circuit is (a) 8W (b) 12W (c) 14.4W (d) 18W Answer: Correct option: (c) Here, read more

JEE-Main - Grade 12 - Physics - Alternating Current - Study ref# 10581

The output of a step-down transformer is measured to be 24V when connected to a 12 W light bulb. The value of the peak current is (a)   (b) read more

JEE-Main - Grade 12 - Physics - Alternating Current - Study ref# 10582

Show a plot of variation of alternating emf versus time generated by a loop of wire rotating in a magnetic field.                             Answer: ... read more

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