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Syllabus

A cylindrical wire is stretched to increase its length by 10%. Calculate the percentage increase in its resistance.

A solenoid with an iron core and bulb are connected to a dc source. how does the brightness of the bulb change when the iron core is removed from the solenoid.??? its urgent

what is wattless current?

what is the dimensional formulas of mutual inductance.

Q. Figure given below shows how the reactance of a capacitor varies with frequency

I) Use this information on graph to calculate the value of capacity of the capacitor.

II) An inductor of inductance L has the same reactance as the capacitor at 100 Hz. Find the value of L.

III) Using the same axes, draw a graph of reactance against frequency for the inductor given in part (ii).

IV) If this capacitor and inductor were connected in series to a resistor of 10 $\Omega $ what would be the impedance of the combination at 300 Hz?

Two bodies of masses m1 and m2 are connected by a light string which passes over a frictionless massless pulley . If the pulley is moving upward with uniform acceleration g/2 , then tension in the string is - 1) 3 m1 m2 g / m1 + m2 ..............2)m1 + m2 g / 4m1 m2 ..........3)2 m1 m2 g / m1 + m2 ..............4)m1 m2 g / m1 + m2 ..............

_{o}what is meant by sharpness of resonance?

1. An electrical element X, when connected to an alternating voltage source, has the current through it leading the voltage by π/2 rad. Identify X and write an expression for its reactance.

2. Draw the graphs showing the variation of reactance of (a) a capacitor and (b) an inductor with the frequency of an a.c. circuit

define watt-less current?

by I = (2 + 3 sin ωt) A, then the effective value of

resulting current in the circuit is

(1)(17/2)

^{1/2}ampere(2) (2/17)

^{1/2}ampere(3)(3/(2)

^{1/2})^{1/2}ampere(4) 3(2)

^{1/2}ampereA sinusoidal voltage of peak value 283 V and frequency 50 Hz is applied to a series LCR circuit in which R = 3 W, 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; (c) the power dissipated in the circuit; and (d) the power factor. In this question for finding P we use P=I^2 R and Irms=I/root2 but why do we divide 283 by 5?

why is 220v ac more dangerous then 22ov dc?

project to investigate the relation between the ratio of

1)output & input voltage

2)no. of turns in secondary & primary coil of a self designed transformer

A 200V variable frequency ac source is connected to series combination of

Solve this :$8.\mathrm{If}\mathrm{current}{\mathrm{I}}_{3}=3\mathrm{A}\mathrm{sin}\mathrm{\omega t}\mathrm{and}{\mathrm{I}}_{2}=4\mathrm{A}\mathrm{cos}\mathrm{\omega t},\mathrm{then}{\mathrm{I}}_{3}\mathrm{is}:\phantom{\rule{0ex}{0ex}}\left(1\right)5\mathrm{A}\mathrm{sin}\left(\mathrm{\omega t}+53\xb0\right)\left(2\right)5\mathrm{A}\mathrm{sin}\left(\mathrm{\omega t}+37\xb0\right)\phantom{\rule{0ex}{0ex}}\left(3\right)5\mathrm{A}\mathrm{sin}\left(\mathrm{\omega t}+45\xb0\right)\left(4\right)5\mathrm{A}\mathrm{sin}\left(\mathrm{\omega t}+30\xb0\right)$

A reactive element , in an AC circuit causes the current flowing.

1. To lead by pi by two

2. to lag in phase by pi by two w.r.t. the applied voltage

Identify the element in each case.

plz answer this question :- A resistor of 200 ohm and a capacitor of 15 micro F are connected in series to a 220V, 50 Hz a.c. source . Calculate the current in the circuit and the r.m.s. voltage across the resistor and capacitor.

what is power factor in an a.c. circuit?

_{0}sin wt is applied across pure inductor. Obtain expression for current flowing in circuit. Hence write expression for instantaneous power supplied by voltage source to inductor. Show that average power supplied over a complete cycle is zero.$168.Inthecircuitshowninfigure{X}_{L}=\frac{{X}_{C}}{2}=R,thepeakvaluecurrent{i}_{0}throughthea.c.sourceis$

$\left(1\right)\frac{\sqrt{5}{V}_{0}}{2R}\left(2\right)\frac{{V}_{0}}{2\sqrt{2}R}\phantom{\rule{0ex}{0ex}}\left(3\right)\frac{{V}_{0}}{2R}\left(4\right)\frac{{V}_{0}}{2\sqrt{3}R}$

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

A variable frequency 230V ac voltage source is connected across a series combination of L=5H,R=40ohm,C=80uF.Calculate

(i)Angular frequency of the source which drives the circuit in resonance,

(ii)Amplitude of current at resonant frequency

(iii)r.m.s voltage across inductor at resonance

full form of LCR circuit?

(i)frequency at which resonance occurs.

(ii)current in the circuit at resonant condition.

what is the definition of quality factor

Power factor of an ac circuit is 0.5. What will be the phase difference between voltage and current in the circuit?

why does a capacitor block dc nd allows ac????

a bulb and a capacitor are connected in series to A.C.source of variable frequency.how will the brightness of the bulb change on increasing the frequency of the A.C. source? give reason for your answer.

ii. Calculate the value of additional capacitor which may be joined suitably to capacitor C that would make the power factor of the circuit unity.

wht is sharpness of resonance in series LCR- circuit ? a resistor of 200 ohm and capacitor of 15 muF

are connected in series 1:0 220V:50Hz ac sorce

a> calculate current in circuit

b>

calculate voltage across resistor and capacitor. is the algebric sum of these voltages more than sorce voltage if yes how?

a)eddy current c)AC

b)DC d)induced current

A series

LCRcircuit withL= 0.12 H,C= 480 nF,R= 23 Ω is connected to a 230 V variable frequency supply.(a)What is the source frequency for which current amplitude is maximum. Obtain this maximum value.(b)What is the source frequency for which average power absorbed by the circuit is maximum. Obtain the value of this maximum power.(c)For which frequencies of the source is the power transferred to the circuit half the power at resonant frequency? What is the current amplitude at these frequencies?(d)What is theQ-factor of the given circuit?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.

A 200v variable frequency a.c source is connected to a series combination of L=5H, e=80uF and R=40 ohms.Calculate:

a) angular frequency of the source to get max. current.

b) the current amplitude at resistance.

c) power dissipation in the circuit at resonance

d) Quality factor.

A series LCR circuit is connected to an A.C source of voltage V and angular frequency w.(omega.) When only the capacitor is removed, the current lags behind the voltage by a phase angle 'phi' and when only the inductor is removed , the current leads teh voltage by tha same phase angle. Find the current flowing and the average power dissipated in teh LCR circuit.? Please REply fast Please.

In an a.c circuit, instantaneous voltage and current are V=200sin300t volts and I=8cos300t Amp respectively. What is the average power dissipated in the circuit ? Why ?

5. (a)State the condition for resonance to occur in series LCR a.c. circuit and derive an expression for

resonant frequency. Mention the factors on which the resonant frequency of a series LCR circuit

depends. Plot a graph showing variation of impedance Of series LCR with frequency of an ac source.(b)

Draw a plot showing the variation of the peak current with frequency of the a.c. source used. Define

quality factor Q of the circuit

what do you mean by Q-factor and whats is its importance ?

through it and this current is in phase with the applied voltage. When another element Y is

connected across the same a.c. source, the same current flows in the circuit but it leads the

voltage by /2 radians.(i) Name the circuit elements X and Y. (ii) Find the current that flows

in the circuit when the series combination of X and Y is connected across the same a.c.

voltage.

Why is the emf maximum when the plane of the armature is parallel to the magnetic filed in an ac generator ?

What is the function of a step up transformer.

The primary coil of an ideal step up transformer has 100 turn and transformation

_{L}= R and power factor of the circuit is P_{1}. When a capacitor with capacitance C such that X_{L}= X_{C}is put in series, the power factor becomes P2. Find P_{1}/ P_{2}.through a switch ‘S’. On closing the switch, show that the sum of the energies in the capacitor

and inductor is constant in time in the free oscillations of the LC circuits.

what is the principle of METAL DETECTORS ?

how coswt = sin(wt+90) possible here??

An inductor 200 MH, capacitor 500µf, resistor 10Ω are connected in series with

Explain principle, working theory of Transformer.

^{-11}, Farad, L = 10^{-5}Henry and R = 100 ohm, when a constant D.C voltage E is applied to the circuit, the capacitor acquires a charge $10\xb0C$. The D.C source is replaced by a sinusoidal voltage source in which the peak voltage E. At resonance the peak value of the charge acquired by the capacitor will be.$\left(A\right){10}^{-15}C\phantom{\rule{0ex}{0ex}}\left(B\right){10}^{-6}C\phantom{\rule{0ex}{0ex}}\left(C\right){10}^{-10}C\phantom{\rule{0ex}{0ex}}\left(D\right){10}^{-8}C$

in a series LCR circuit the voltages across an inductor,capacitor, n a resistor are 30V,30V n 60V respectively.wat is the phase difference b/w the applied voltage n current in the circuit.??

Give principle construction working of AC generator.

When an alternating voltage of 220V is applied across a device X, a current of 0.5A

flows through the circuit and is in phase with the applied voltage. When the same

voltage is applied across another device Y the same current flows through the

circuit but it leads the applied voltage by /2 rad.

(a) Name the devices X and Y.

(b) Calculate the current flowing in the circuit when same voltage is applied across

the series combinations of X and Y.

Q1.Show that in an ideal transformer when the voltage is stepped up by certain factor the current get stepped down by the same factor.

_{0}sinwt.the variation of voltage,current and power in one complete cycle is shown in the following.which curve shows power consumption over a full cycle?identify the deviceX

the current flowing through a pure inductor of inductance 4mH is i=12 cos 300 t ampere.what is the

i) rms

ii) average value of the current for the complete cycle