Alternating current practice · Medium

The transformation ratio in the step-up transformer is

The household supply of electricity is at $220 \mathrm{~V}$ (rms value) and $50 \mathrm{~Hz}$. Find the peak voltage and the least possible time in which the voltage can change from the rms value to zero.

A capacitor of capacitance $1 \mu \mathrm{F}$ is charged to a potential of $1 \mathrm{~V}$. It is connected in parallel to an inductor of inductance $10^{-3} \mathrm{~H}$. The maximum current that will flow in the circuit has the value

An AC source of variable frequency is applied across a series L-C-R circit . At a frequency double the resonance frequency. The impedance is $\sqrt{10}$ times the minimum impedance. The inductive reactance is

A series LCR circuit is connected to an ac voltage source. When $\mathrm{L}$ is removed from the circuit, the phase difference
between current and voltage is $\frac{\pi }{3}$. If instead $\mathrm{C}$ is removed from the circuit, the phase difference is again $\frac{\pi }{3}$ between
current and voltage. The power factor of the circuit is:

The power dissipated in an AC circuit is zero if the circuit is

Alternating current in circuit is given by $I=I_0 \sin 2 \pi$ nt. Then the time taken by the current to rise from zero to r.m.s. value is equal to

The average power dissipation in a pure capacitance in AC circuit is:

A transformer operating at primary voltage $8 \mathrm{kV}$ and secondary voltage $160 \mathrm{~V}$ serves a load of $80 \mathrm{~kW}$. Assuming the transformer to be ideal with purely resistive load and working on unity power factor, the loads in the primary and secondary circuit would be

Find the maximum value of current when an inductance of one henry is connected to an a.c. source of 200 volts, $50 \mathrm{~Hz}$

Statement (A): If current varies sinusoidally the average power consumed in a cycle is zero.

Statement (B): If current varies sinusoidally the average current is zero in a complete cycle.

When $100 \mathrm{V} \mathrm{~DC}$ is applied across a coil, a current of $4 \mathrm{~A}$ flows through it. When $200 \mathrm{V} \mathrm{AC}$ at $100 \mathrm{~Hz}$ is applied to the same coil, a current of amplitude $\sqrt{2}$ A flows. The reactance of the coil is

An inductor and a resistor are connected in series with an ac source. In this circuit.

An inductance of $0.05 / \pi$ Henry and a 12 ohm resistance with resistance (negligible) are connected in series combination. Across the end of this electric circuit is connected a $130 \mathrm{~V}$ alternating voltage of frequency 50 cycles/second. Find out the alternating current in the circuit and potential difference across the inductance and that across the resistance.

The instantaneous values of voltage and current in an ac circuit are represented by $V = 2\sqrt 2 \sin \left( {100\pi t + \frac{\pi }{4}} \right)$ $i = \frac{1}{{\sqrt 2 }}\sin 100\pi t$. The angular frequency of ac is

The phase difference between the current and voltage of LCR circuit in series combination at resonance is

Which of the following quantities remains constant in a step-down transformer ?

Statement (A): With increase in frequency of $\mathrm{AC}$ supply inductive reactance increases.

Statement (B): With increase in frequency of $\mathrm{AC}$ supply capacitive reactance increase

A soft iron rod is inserted in the solenoid. After this what will be the effect on the brightness of the bulb?

Power consumed in A.C circuit is zero then the ac source could be connected to

Statement (A): Step up transformer converts low voltage, high current to high voltage, low current.

Statement (B): Transformer works on both ac and dc.

A resistor of R=6Ω, an inductor of L = 1 H and a capacitor of C=17.36 μF are connected in series with an AC source. Find the Q - factor.

A bulb rated $60 \mathrm{~W}$ at $220 \mathrm{~V}$ is connected across a household supply of alternating voltage of $220 \mathrm{~V}$. Calculate the maximum instantaneous current through the filament.

Consider an a.c circuit having resistor of resistance $R$ and an inductor having reactance $X_L.$ If voltage leads the current by an angle $60^{\circ},$ then

An LC current contains inductance $\mathrm{L}=1 \mu \mathrm{H}$ and capacitance $\mathrm{C}=0.01 \mu \mathrm{F}$. The wavelength of electromagnetic wave generated is nearly :-

A 220 V, 50 Hz ac source is connected to an inductance of 0.2 H and a resistance of 20 ohm in series. What is the current in the circuit

Assertion(A): Two identical heaters are connected to two
different sources one DC and other AC having same
potential difference across their terminals. The heat
produced in heater supplied with DC source is greater.

Reason (R): The net impedance of an AC source is
greater than resistance.

A lamp (pure resistance) is connected in series with a capacitor

A) When a dc source is connected to the combination, the lamp will not glow in steady state

B) When ac source is connected to the combination, the brightness of glow of lamp increases with increases of frequecncy of ac.

A Daniel cell is connected to the primary coil of a transformer. If the output voltage of the Daniel cell is $10 \mathrm{~V}$, and the ratio of secondary to primary coil turns of transformer is 2 , then the voltage in the secondary will be

A charged capacitor is discharged through a resistance. The time constant of the circuit is $\eta$. Then, the value of time constant for the power dissipated through the resistance will be