Alternating Current · Physics · MHT CET

The power factor of an R-L circuit is $$\frac{1}{\sqrt{2}}$$. If the frequency of $$\mathrm{AC}$$ is doubled the power factor will now be

An alternating voltage $$E=200 \sqrt{2} \sin (100 t)$$ volt is connected to a $$1 \mu \mathrm{f}$$ capacitor through an a.c. ammeter. The reading of t...

What will be the phase difference between virtual voltage and virtual current when current in the circuit is wattless?

A coil having an inductance of $$\frac{1}{\pi} \mathrm{H}$$ is connected in series with a resistance of $$300 \Omega$$. If $$20 \mathrm{~V}$$ from a $...

An alternating voltage is applied to a series LCR circuit. If the current leads the voltage by $$45^{\circ}$$, then $$\left(\tan 45^{\circ}=1\right)$$...

For a purely inductive or a purely capacitive circuit, the power factor is

The reciprocal of the total effective resistance of LCR a.c. circuit is called

The number of turns in the primary and the secondary of a transformer are 1000 and 3000 , respectively. If $$80 \mathrm{~V} \mathrm{~AC}$$ is applied ...

A group of lamps having total power rating of $$1000 \mathrm{~W}$$ is supplied by an AC voltage of $$E=200 \sin \left(310 t+60^{\circ}\right)$$, the r...

At a particular angular frequency, the reactance of capacitor and that of inductor is same. If the angular frequency is doubled, the ratio of the reac...

In a $$L$$-$$R$$ circuit the inductive reactance is equal to the resistance $R$ in the circuit. An emf $$E=E_0 \cos \omega t$$ is applied to the circu...

In an oscillating LC circuit, the maximum charge on the capacitor is '$$Q$$'. When the energy is stored equally between the electric and magnetic fiel...

With increase in frequency of a.c. supply, the impedance of an L-C-R series circuit

In an a.c. circuit the instantaneous current and emf are represented as $$\mathrm{I}=\mathrm{I}_0, \sin [\omega \mathrm{t}-\pi / 6]$$ and $$\mathrm{E}...

When an inductor '$$L$$' and a resistor '$$R$$' in series are connected across a $$15 \mathrm{~V}, 50 \mathrm{~Hz}$$ a.c. supply, a current of $$0.3 \...

An a.c. source of $$15 \mathrm{~V}, 50 \mathrm{~Hz}$$ is connected across an inductor (L) and resistance (R) in series R.M.S. current of $$0.5 \mathrm...

Resistor of $$2\Omega$$, inductor of $$100 \mu \mathrm{H}$$ and capacitor of $$400 \mathrm{pF}$$ are connected in series across a source of $$\mathrm{...

In the given circuit, r.m.s. value of current through the resistor $$\mathrm{R}$$ is ...

In the given circuit, if $$\frac{\mathrm{dI}}{\mathrm{dt}}=-1 \mathrm{~A} / \mathrm{s}$$ then the value of $$\left(V_A-V_B\right)$$ at this instance w...

An inductor of $$0.5 \mathrm{~mH}$$, a capacitor of $$20 ~\mu \mathrm{F}$$ and a resistance of $$20 \Omega$$ are connected in series with a $$220 \mat...

The a.c. source is connected to series LCR circuit. If voltage across $$R$$ is $$40 \mathrm{~V}$$, that across $$\mathrm{L}$$ is $$80 \mathrm{~V}$$ an...

In a series LCR circuit, $$\mathrm{C}=2 \mu \mathrm{F}, \mathrm{L}=1 \mathrm{mH}$$ and $$\mathrm{R}=10 \Omega$$. The ratio of the energies stored in t...

The a.c. source of e.m.f. with instantaneous value '$$e$$' is given by $$e=200 \sin (50 t)$$ volt. The r.m.s. value of current in a circuit of resista...

With the gradual increase in frequency of an a. c. source, the impedance of an LCR series circuit

In series LCR circuit, the voltage across the inductance and the capacitance are not

With an alternating voltage source of frequency '$$f$$', inductor '$$L$$', capacitor '$$C$$' and resistance '$$R$$' are connected in series. The volta...

The capacitive reactance of a capacitor '$$C$$' is $$\mathrm{X} \Omega$$. Both, the frequency of a.c. supply and capacitance of the above capacitor ar...

A $$100 \mathrm{~mH}$$ coil carries a current of $$1 \mathrm{~A}$$. Energy stored in the form of magnetic field is

In the circuit given below, the current through inductor is $$0.9 \mathrm{~A}$$ and through the capacitor is $$0.6 \mathrm{~A}$$. The current drawn fr...

The inductive reactance of a coil is '$$\mathrm{X}_{\mathrm{L}}$$'. If the inductance of a coil is tripled and frequency of a.c. supply is doubled, th...

In the circuit shown the ratio of quality factor and the bandwidth is ...

In a series LR circuit, $$X_L=R$$, power factor is $$P_1$$. If a capacitor of capacitance $$C$$ with $$X_C=X_L$$ is added to the circuit the power fac...

An e.m.f. $$E=4 \cos (1000 t)$$ volt is applied to an LR circuit of inductance $$3 \mathrm{~mH}$$ and resistance $$4 ~\Omega$$. The maximum current in...

An alternating voltage of frequency '$$\omega$$' is induced in electric circuit consisting of an inductance '$$L$$' and capacitance '$$C$$', connected...

The reactance of capacitor at $$50 \mathrm{~Hz}$$ is $$5 \Omega$$. If the frequency is increased to $$100 \mathrm{~Hz}$$, the new reactance is

The coil of an a.c. generator has 100 turns, each of cross-sectional area $$2 \mathrm{~m}^2$$. It is rotating at constant angular speed $$30 ~\mathrm{...

A capacitor, an inductor and an electric bulb are connected in series to an a.c. supply of variable frequency. As the frequency of the supply is incre...

In an $$\mathrm{AC}$$ circuit, the current is $$\mathrm{i}=5 \sin \left(100 \mathrm{t}-\frac{\pi}{2}\right) \mathrm{A}$$ and voltage is $$\mathrm{e}=2...

A capacitor of capacitance $$50 \mu \mathrm{F}$$ is connected to a.c. source $$\mathrm{e}=220 \sin 50 \mathrm{t}$$ ($$\mathrm{e}$$ in volt, $$\mathrm{...

The resistance offered by an inductor $$\left(X_L\right)$$ in an a.c. circuit is

A coil having an inductance of $$\frac{1}{\pi} \mathrm{H}$$ is connected in series with a resistance of $$300 \Omega$$. If A.C. Source $$(20 \mathrm{~...

In a full wave rectifier circuit without filter, the output current is

A rejector circuit is the resonant circuit in which

In series LCR circuit, at resonance the peak value of current will be [$$\mathrm{E_0}$$ is peak emf, R is resistance, $$\omega \mathrm{L}$$ is inducti...

An alternating e.m.f. is $$\mathrm{e}=\mathrm{e}_0 \sin \omega \mathrm{t}$$. In what time the e.m.f. will have half its maximum value, if '$$\mathrm{e...

A step up transformer operates on $$220 \mathrm{~V}$$ and supplies current of $$2 \mathrm{~A}$$. The ratio of primary and secondary windings is $$1: 2...

In the part of an a.c. circuit as shown, the resistance $$R=0.2 \Omega$$. At a certain instant $$(\mathrm{V_A-V_B})= 0.5 \mathrm{~V}, \mathrm{I}=0.5 \...

In the circuit shown in the figure, a.c. source gives voltage $$\mathrm{V}=20 \cos (2000 \mathrm{t})$$. Impedance and r.m.s. current respectively will...

Which graph shows the correct variation of r.m.s. current 'I' with frequency 'f' of a.c. in case of (LCR) parallel resonance circuit? ...

The peak value of an alternating emf '$$\mathrm{e}$$' given by $$\mathrm{e}=\mathrm{e}_0 \cos \omega \mathrm{t}$$ is 10 volt and its frequency is $$50...

A circuit containing resistance R$$_1$$, inductance L$$_1$$ and capacitance C$$_1$$ connected in series resonates at the same frequency 'f$$_0$$' as a...

A series L-C-R circuit containing a resistance of $$120 ~\Omega$$ has angular frequency $$4 \times 10^5 \mathrm{~rad} \mathrm{~s}^{-1}$$. At resonance...

For series LCR circuit, which one of the following is a CORRECT statement?

In an LCR series a.c. circuit, the voltage across each of the components L, C and R is 60 V. The voltage across the LC combination is

If we increase the frequency of an a.c. supply, then inductive reactance

A capacitor of capacity '$$C$$' is charged to a potential '$$V$$'. It is connected in parallel to an inductor of inductance '$$\mathrm{L}$$'. The maxi...

A step down transformer is used to reduce the main supply from '$$V_1$$' volt to '$$V_2$$' volt. The primary coil draws a current '$$\mathrm{I}_1$$' $...

For the circuit shown below, instantaneous current through inductor '$$\mathrm{L}$$' and capacitor '$$\mathrm{C}$$' is respectively. ...

A parallel plate capacitor having plates of radius 6 cm has capacitance 100 pF. It is connected to 230 V a.c. supply with angular frequency 300 rad/s....

A step down transformer has turns ratio $$20: 1$$. If $$8 \mathrm{~V}$$ is applied across $$0.4 \mathrm{~ohm}$$ secondary then the primary current wil...

An a.c. source of angular frequency '$$\omega$$' is fed across a resistor '$$R$$' and a capacitor '$$C$$' in series. The current registered is I. If n...

In an a.c. circuit, a resistance R = 40 $$\Omega$$ and an inductance 'L' are connected in series. If the phase angle between voltage and current is 45...

The frequency of the output signal of an LC oscillator circuit is '$$\mathrm{F}$$' Hz with a capacitance of 0.1 $$\mu \mathrm{F}$$. If the value of th...

In LCR series resonant circuit, at resonance, voltage across 'L' and 'C' will cancel each other because they are

The inductive reactance of a coil is R$$\Omega$$. If the inductance of a coil is doubled and frequency of a.c. supply is also doubled then the new ind...

Three pure inductors each of inductance 6H are connected as shown in the figure. Their equivalent inductance between the points 'P' and 'Q' is ...

The instantaneous value of an alternating current is given by $$\mathrm{i}=50 \sin (100 \pi \mathrm{t})$$. It will achieve a value of $$25 \mathrm{~A}...

In a step up transformer, which one of the following statements is correct?

In the graphical representation of e.m.f. '$$\mathrm{e}$$' and current '$$\mathrm{i}$$' versus '$$\omega \mathrm{t}$$' for an a.c. circuit, both emf a...

An alternating voltge is represented by $$\mathrm{V}=80 \sin (100 \pi \mathrm{t}) \cos (100 \pi \mathrm{t})$$ volt. The peak voltage is

A series combination of resistor 'R' and capacitor 'C' is connected to an a.c. source of angular frequency '$$\omega$$'. Keeping the voltage same, if ...

An inductive coil has a resistance of $$100 ~\Omega$$. When an a.c. signal of frequency $$1000 \mathrm{~Hz}$$ is applied to the coil the voltage leads...

In an ideal step down transformer, out of the following quantities, which quantity increases in the secondary coil?

A series LCR circuit with resistance (R) $$500 ~\mathrm{ohm}$$ is connected to an a.c. source of $$250 \mathrm{~V}$$. When only the capacitance is rem...

When a d.c. voltage of $$200 \mathrm{~V}$$ is applied to a coil of self-inductance $$\left(\frac{2 \sqrt{3}}{\pi}\right) \mathrm{H}$$, a current of $$...

An inductor coil wound uniformly has self inductance 'L' and resistance 'R'. The coil is broken into two identical parts. The two parts are then con...

An inductor coil takes current 8A when connected to an 100 V and 50 Hz a.c. source. A pure resistor under the same condition takes current of 10A. If ...

An AC circuit contains resistance of $12 \Omega$ and inductive reactance $5 \Omega$. The phase angle between current and potential difference will be...

A step-up transformer has 300 turns of primary winding and 450 turns of secondary winding. A primary is connected to 150 V and the current flowing thr...

An alternating emf of $$0.2 \mathrm{~V}$$ is applied across an L-C-R series circuit having $$R=4 \Omega, C=80 \mu \mathrm{F}$$ and $$L=200 \mathrm{~mH...

A 220 V input is supplied to a transformer. The output circuit draws a current of 2.0 A at 440 V . If the ratio of output to input power is 0.8 , then...

A coil has inductance 2 H . The ratio of its reactance, when it is connected first to an $A C$ source and then to DC source, is

An alternating voltage is given by $E=100 \sin \left(\omega+\frac{\pi}{6}\right) \mathrm{V}$. The voltage will be maximum for the first time when is [...

In a series $L C R$ circuit $R=300 \Omega, L=0.9 \mathrm{H}$, $C=2 \mu \mathrm{~F}, \omega=1000 \mathrm{rad} / \mathrm{s}$. The impedance of the circu...