Self Studies

Alternating Cur...

TIME LEFT -
  • Question 1
    1 / -0

    A capacitor (C=40μ=40\mu F) is connected through a resistor (R=2.5R=2.5MΩ\Omega) across a battery of negligible internal resistance of voltage 1212 volts. The time after which the potential difference across the capacitor becomes three times to that of resistor is (in 2=0.6932=0.693).

  • Question 2
    1 / -0

    Directions For Questions

    Consider the parallel resonant circuit shown in adjacent figure. One branch contains an inductor of inductance LL and a small ohmic resistance RR, whereas the other branch contains a capacitor of capacitance CC. The circuit is fed by a source of alternating emf
    E=E0eiωt=E0sinωtE={ E }_{ 0 }{ e }^{ i\omega t }={ E }_{ 0 }\sin { \omega t }
    The impedance of inductor branch, Z1=R+jωL{ Z }_{ 1 }=R+j\omega L
    The impedance of capacitor branch, Z2=(1/jωC){ Z }_{ 2 }=\left( 1/j\omega C \right)
    Net impedance ZZ of the two parallel branches is given by
    1Z=1Z1+1Z2=1R+jωL+jωC=RR2+L2ω 2+jω[CLR2+L2ω 2 ]\cfrac { 1 }{ Z } =\cfrac { 1 }{ { Z }_{ 1 } } +\cfrac { 1 }{ { Z }_{ 2 } } =\cfrac { 1 }{ R+j\omega L } +j\omega C=\cfrac { R }{ { R }^{ 2 }+{ L }^{ 2 }{ \omega  }^{ 2 } } +j\omega \left[ C-\cfrac { L }{ { R }^{ 2 }+{ L }^{ 2 }{ \omega  }^{ 2 } }  \right]
    The current flowing in the circuit
    I=EZ=E[RR2+L2ω 2+jω[CLR2+L2ω 2 ] ]I=\cfrac { E }{ Z } =E\left[ \cfrac { R }{ { R }^{ 2 }+{ L }^{ 2 }{ \omega  }^{ 2 } } +j\omega \left[ C-\cfrac { L }{ { R }^{ 2 }+{ L }^{ 2 }{ \omega  }^{ 2 } }  \right]  \right]
    For resonance to occur, the current must be in phase with the applied emf. For this, the reactive component of current should be zero, ie
    ω(CLR2+L2ω 2 )=0\omega \left( C-\cfrac { L }{ { R }^{ 2 }+{ L }^{ 2 }{ \omega  }^{ 2 } }  \right) =0
    This gives resonant angular frequency
    ω r=1LCR2L2 \quad { \omega  }_{ r }=\sqrt { \cfrac { 1 }{ LC } -\cfrac { { R }^{ 2 } }{ { L }^{ 2 } }  }
    At parallel circuit resonance, the impedance is maximum and current is minimum. Parallel resonant circuit is sometimes called the anti-resonance in order to distinguish from series resonance.


    ...view full instructions

    Find the impedance of AC circuit at resonance shown in the adjacent figure.

  • Question 3
    1 / -0

    An ac source of angular frequency ω\omega is fed across a resistor R and a capacitor C in series. The current registered is II. If now the frequency of source is changed to ω/3\omega/3 (but maintaining the same voltage), the current in the circuit is found to be halved. The ratio of reactance at the original frequency ω\omega will be:

  • Question 4
    1 / -0

    Determine the characteristic impedance of a transmission line which has a capacitance of 35pF/ft and an inductance of 0.25μH/ft\mu H/ft

  • Question 5
    1 / -0

    The reciprocal of impedance is called

  • Question 6
    1 / -0

    In a series LCRLCR circuit K=200 ΩK=200\ \Omega and the voltage and frequency of the main supply are 220 V220\ V and 50 Hz50\ Hz respectively. On taking out the capacitor from the circuit, the current leads the voltage by 30o{30}^{o}. On taking out the indicator from the circuit the current leads the voltage by 30o{30}^{o}. The power dissipated in the LCRLCR circuit is :

  • Question 7
    1 / -0

    In the series LCRLCR circuit as shown in figure, the voltmeter and ammeter readings are:

  • Question 8
    1 / -0

    The characteristic impedance of a co-axial cable is of order of:

  • Question 9
    1 / -0

    If instantaneous current in a circuit is given by l=(2+3sinl = (2 + 3 sin ωt)A\omega t)A, then the effective value of resulting current in the circuit is:

  • Question 10
    1 / -0

    Which of the following option is correct for an ideal capacitor connected to a sinusoidal voltage source over a complete cycle?

Submit Test
Self Studies
User
Question Analysis
  • Answered - 0

  • Unanswered - 10

  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 8
  • 9
  • 10
Submit Test
Self Studies Get latest Exam Updates
& Study Material Alerts!
No, Thanks
Self Studies
Click on Allow to receive notifications
Allow Notification
Self Studies
Self Studies Self Studies
To enable notifications follow this 2 steps:
  • First Click on Secure Icon Self Studies
  • Second click on the toggle icon
Allow Notification
Get latest Exam Updates & FREE Study Material Alerts!
Self Studies ×
Open Now