Recent questions tagged ch7

Two different coils have self inductance $L_1=8\;mH$ and $L_2=2\;mH$. At a certain instant , the current in the two coils is increasing at the same constant rate and the power supplied to the two coils is the same . Find the ratio of the current and energy stored.

asked Sep 27, 2016 by meena.p

1 answer

Two different coils have self inductance $L_1=8\;mH$ and $L_2=2\;mH$. At a certain instant , the current in the two coils is increasing at the same constant rate and the power supplied to the two coils is the same . Find the ratio of induced voltage at that instant

asked Sep 27, 2016 by meena.p

1 answer

1 Mw power is to be delivered from a power station to a town $10\;km$ away. One uses a pair of cer wires $0.5\;cm$ for this purpose . Calculate the fraction of ohmic losses to power transmitted if power is transmitted comment on the feasibility of doing this ?

asked Sep 27, 2016 by meena.p

1 answer

An electrical drive draws 2 kw power from AC mains [ Voltage $223 V(rms) = \sqrt {50,000}\;v$ ]. The current differs (lags) in phase by $\phi (\tan \phi = -\large\frac{-3}{4} )$ as compared to voltage . Find $I_{max}$ another device has twice the value of $R,X_c$ and $X_L$. How are the answers affected ?

asked Sep 27, 2016 by meena.p

1 answer

An electrical drive draws 2 kw power from AC mains [ Voltage $223 V(rms) = \sqrt {50,000}\;v$ ]. The current differs (lags) in phase by $\phi (\tan \phi = -\large\frac{-3}{4} )$ as compared to voltage . Find $ X_C - X_L$

asked Sep 26, 2016 by meena.p

1 answer

An electrical drive draws 2 kw power from AC mains [ Voltage $223 V(rms) = \sqrt {50,000}\;v$ ]. The current differs (lags) in phase by $\phi (\tan \phi = -\large\frac{-3}{4} )$ as compared to voltage . Find R

asked Sep 26, 2016 by meena.p

1 answer

Explain why the reactant offered by an inductor increased with increased frequency of an alternating voltage.

asked Sep 26, 2016 by meena.p

1 answer

Explain why the reactant provided by a capital to an alternating current decreases with increasing frequency .

asked Sep 26, 2016 by meena.p

1 answer

A $60\;w$ load is connected to the secondary of a transformer whose primary draws line voltage. If a current of $0.54\;A$ flows in the load, what is the current in the primary coil ? Comment on the type of transformer bring used ?

asked Sep 26, 2016 by meena.p

1 answer

A Coil of $0.01$ Henry inductance and 1 ohm resistance is connected to $200 \;volt,50 Hz,ac $ supply . Find the impedance of the circuit and time lag between max. alternating voltage and current .

asked Sep 26, 2016 by meena.p

1 answer

Both alternating current and direct current are measured in ampere. But how is the ampere defined defined for an alternating current .

asked Sep 26, 2016 by meena.p

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How does the sign of the phase angle $\phi$ , big which the supply voltage leads the current in an LCR series circuit , change as the supply frequency is gradually increased from very low to very high values ?

asked Sep 23, 2016 by meena.p

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Can the instantaneous power output of an ac source ever he negative ? can the average power output be negative ?

asked Sep 23, 2016 by meena.p

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In LC circuit , is considered analogous to a harmonically oscillating spring block system, which energy of LC circuit would be analogous to potential energy and which one analogous to kinetic energy ?

asked Sep 22, 2016 by meena.p

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The line that draws power supply to your house from street has

asked Sep 22, 2016 by meena.p

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For an LCR circuit , the power transferred forms the diving source to the drives oscillator is $P= I^2 z \cos \phi$

asked Sep 22, 2016 by meena.p

1 answer

Electrical energy is transmitted over large distance at high alternating voltage . Which of the following statement are correct ?

asked Sep 22, 2016 by meena.p

1 answer

In an alternating current circuit consisting of elements in series, the current increases on increasing the frequency of supply . Which of the following elements are likely to continue the circuit ?

asked Sep 22, 2016 by meena.p

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As the frequency of an ac circuit increase, the current first increase and then decrease . What combination of circuit elements is most likely to comprise the circuit ?

asked Sep 22, 2016 by meena.p

1 answer

The output of a step down transformer is measured to be $24\;v$ when connected to a 12 walt light bulb. The value of the peak current is

asked Sep 22, 2016 by meena.p

1 answer

An inductor of a reactance $1 \Omega$ and a resistor of $2 \Omega$ are connected in series to the terminals of a$6\;v(r.m.s)$ a.c source. The power dissipated in the circuit is

asked Sep 22, 2016 by meena.p

1 answer

Which of the following combination should be selected for better turning of an LCR circuit used for communication ?

asked Sep 21, 2016 by meena.p

1 answer

The voltmeter the resonant frequency in an L.C.R series circuit with a generator .

asked Sep 21, 2016 by meena.p

1 answer

When a voltage measuring device is connected to AC mains , the meter shows the steady input voltage opf $220\;v$ This means

asked Sep 21, 2016 by meena.p

1 answer

An alternating current generator has an internal resistance $R_g$ and an internal reluctance $X_g$.It is used to supply power to a passive loud consisting of a resistance $R_g$ and a reluctance $x_L$ . For maximum power to be delivered from the generator to the load, the value of $X_L$ is equal to

asked Sep 21, 2016 by meena.p

1 answer

If the rms current in a 50 Hz a.c circuit is $5\;A$ , the value of the current $ \large\frac{1}{300}$ seconds after its value becomes zero is

asked Sep 21, 2016 by meena.p

1 answer

A small town with a demand of $800\;kw$ of electric power at $220\;v$ is situated $15\;km$ away from an electric plant generating power at $440\;v$. The resistance of the two line wires carrying power is $0.5\;\Omega$ per km. The town gets power from the lines through a $40,000-220\;v$ Step down transformation. Neglect leaked losses . hence explain why high voltage transmission is preferred .

asked Sep 21, 2016 by meena.p

1 answer

A small town with a demand of $800\;kw$ of electric power at $220\;v$ is situated $15\;km$ away from an electric plant generating power at $440\;v$. The resistance of the two line wires carrying power is $0.5\;\Omega$ per km. The town gets power from the lines through a $4000-220\;v$ Step down transformation at a substation in the town .Characterize the step up transformer at the plant

asked Sep 21, 2016 by meena.p

1 answer

A small town with a demand of $800\;kw$ of electric power at $220\;v$ is situated $15\;km$ away from an electric plant generating power at $440\;v$. The resistance of the two line wires carrying power is $0.5\;\Omega$ per km. The town gets power from the lines through a $4000-220\;v$ Step down transformation at a substation in the town . How much power must the plant supply , assuming there is negligible power loss due to leakage ?

asked Sep 21, 2016 by meena.p

1 answer

A small town with a demand of $800\;kw$ of electric power at $220\;v$ is situated $15\;km$ away from an electric plant generating power at $440\;v$. The resistance of the two line wires carrying power is $0.5\;\Omega$ per km. The town gets power from the lines through a $4000-220\;v$ Step down transformation at a substation in the town . Estimate the power loss in the form of heat

asked Sep 21, 2016 by meena.p

1 answer

At a hydroelectric power plant , the water pressure head is at a height of 300 m and the water flow available is $100 m^3 s^{-1} $. If the turbine generator efficiency is $60\%$ estimate the electric power available from the plant $(g= 9.8 ms^{-2})$

asked Sep 20, 2016 by meena.p

1 answer

A power transmission line feeds input power at $2300\;v$ to a step down transformer , with its primary winding's having $4000$ turns. What should be the number of turns in the secondary windings in order to get out put power at $230\;v$

asked Sep 20, 2016 by meena.p

1 answer

Why is choke coil needed in the use of flourscent takes with a.c mains? Why can we not use an ordinary resistor instead of choke coil ?

asked Sep 20, 2016 by meena.p

1 answer

A check coil in series with a lamp is connected to a d.c line. The lamp is seen to shine brightly and insertion of an iron core in the choke causes no change in the lamps brightness. Predict the corresponding observation if the connection is to as a.c line

asked Sep 20, 2016 by meena.p

1 answer

An applied voltage signal consists of a super position of a d.c voltage and a.c voltage of high frequency . The circuit consists of an inductor and a capacitor in series. will the d.c signal will appear across c and the a.c signal will appear across L ? At high frequencies

asked Sep 20, 2016 by meena.p

1 answer

A capacitor is used in the primary circuit of an induction coil . Why ?

asked Sep 20, 2016 by meena.p

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In any a.c circuit is the applied instantaneous voltages equal to the algebraic sum of the instantaneous voltages across the series element of the circuit ? Is the same true for r.m.s voltage?

asked Sep 20, 2016 by meena.p

1 answer

Obtain the resonant frequency and Q- factor of a series circuit with $L= 3.0 \;H,C= 27\mu F$ and $R= 7.4 \Omega$ . It is desired to improve the sharpness of resonance of the circuit by reducing its full width at half max. by a factor of 2. suggest a suitable way

asked Sep 20, 2016 by meena.p

1 answer

A series LCR circuit with $L= 0.12 H,C= 480\;nF,R= 23 \Omega $ is connected to a $230\;v$ variable frequency supply .For What frequencies of the circuit half the power at resonant frequency . What is the Q factor of the given circuit ?

asked Sep 19, 2016 by meena.p

1 answer

A series LCR circuit with $L= 0.12 H,C= 480\;nF,R= 23 \Omega $ is connected to a $230\;v$ variable frequency supply .For What frequencies of the circuit half the power at resonant frequency . What is the current amplitute at these frequencies?

asked Sep 19, 2016 by meena.p

1 answer

A series LCR circuit with $L= 0.12 H,C= 480\;nF,R= 23 \Omega $ is connected to a $230\;v$ variable frequency supply .What is the source frequency for which average power absorbed by the circuit is maximum ? obtain the value of this mass power

asked Sep 19, 2016 by meena.p

1 answer

A series LCR circuit with $L= 0.12 H,C= 480\;nF,R= 23 \Omega $ is connected to a $230\;v$ variable frequency supply .

asked Sep 19, 2016 by meena.p

1 answer

Suppose a circuit containing 80 mH and a $60 \mu F$ capacitor in series is connected to a $230\;V, 50 \;Hz$ Supply . The resistance in the circuit is negligible . obtain the average power transferred to each element of the circuit , and the total power absorbed .

asked Sep 19, 2016 by meena.p

1 answer

A circuit containing a $80\;mH$ inductor and a $60 \mu F$ capacitor in series is connected to a $230\;v,50\;Hz$ supply . The resistance in the circuit is negligible. What is the total average power absorbed by the circuit ?

asked Sep 19, 2016 by meena.p

1 answer

A circuit containing a $80\;mH$ inductor and a $60 \mu F$ capacitor in series is connected to a $230\;v,50\;Hz$ supply . The resistance in the circuit is negligible. What is the average power transferred to capacitor ?

asked Sep 16, 2016 by meena.p

1 answer

A circuit containing a $80\;mH$ inductor and a $60 \mu F$ capacitor in series is connected to a $230\;v,50\;Hz$ supply . The resistance in the circuit is negligible. What is the average power transferred to inductor ?

asked Sep 16, 2016 by meena.p

1 answer

A circuit containing a $80\;mH$ inductor and a $60 \mu F$ capacitor in series is connected to a $230\;v,50\;Hz$ supply . The resistance in the circuit is negligible. obtain the current amplitude and V.M.S value of potential drop across each element .

asked Sep 16, 2016 by meena.p

1 answer

A circuit containing a $80\;mH$ inductor and a $60 \mu F$ capacitor in series is connected to a $230\;v,50\;Hz$ supply . The resistance in the circuit is negligible. obtain the current amplitude and V.M.S value

asked Sep 15, 2016 by meena.p

1 answer

Keeping the source frequency equal to the resonating frequency of the series LCR circuit , if the three elements L,C and R , an arranged in parallel , show that the total current in the parallel LCR circuit, is a minimum at this frequency . obtain the r.m.s value of current in each branch of the circuit for the elements and source whose values are $L= 5.0 \;H,C= 80\;\mu F, R= 40 \Omega$ for this frequency

asked Sep 15, 2016 by meena.p

1 answer

A $100 \mu F$ capacitor in series with a $40 \Omega$ resistance is connected to a $110\;v,12\;kHz$ supply's Is the statement that a capacitor is a conductor at very high frequencies . True or false ?

asked Sep 15, 2016 by meena.p

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