Question 1 :
The primary to secondary turns ratio of a transformer is given as 2 : 3. If the current through the primary coil is 3 A, then the current through load resistance is<br/>
Question 3 :
Whenthe values of inductance and capacitance in an $L-C$ circuit are $0.5\ H$ and $8\ \mu$F respectively then currentinthe circuit is maximum. The angular frequency ofalternatinge.m.f. applied in the circuit will be
Question 4 :
A certain series resonant circuit has a bandwidth of $2 kHz$. If the existing coil is replaced with one having a higher value of $Q$, the bandwidth will<br/>
Question 5 :
A transformer is used to light a $120 W$,$24 V$lamp from$240 V$a.c. mains. The current in the main cableis$0.6 A$.The efficiency of the transformer is
Question 6 :
What do we name the  device which increases the emf ?<br/>
Question 8 :
In an ac circuit with voltage V and current I, the power dissipated is
Question 10 :
The power loss in an $AC$ circuit is $E_{rms}$ $I_{rms}$, when in the circuit there is only
Question 11 :
In an ac circuit, $V$ and $I$ are given by $V=50\sin { 50t } $ and $I=100\sin { \left( 50t+\pi /3 \right) } mA$. The power dissipated in the circuit.
Question 12 :
<span class="wysiwyg-font-size-small">The current and voltage functions in an AC circuit are$i = 100\sin 100tmA$ , $V = 100\sin \left( {100t + \cfrac{\pi }{3}} \right)V$ The power dissipated in the circuit is<br/>
Question 13 :
A step down transformer reduces 220V to 11V.The primary coil draws 5A current and secondary coil supplies 90A.Efficiency of the transformer will be
Question 14 :
A loss free transformer has $500$ turns on its primary winding and $2500$ in secondary. The meters of the secondary indicate $200$ volts at $8$ amperes under these conditions. The voltage and current in theprimary is
Question 15 :
In LCR series circuit, an alternating e.m.f. 'e' and current 'i' are given by the equations $e=100\sin(100t)$volt, $i=100\sin\left(100+\displaystyle\frac{\pi}{3}\right)$mA. The average power dissipated in the circuit will be<br/>
Question 17 :
In an oscillating system, a restoring force is a must. In an L - C circuit, restoring force is provide by
Question 18 :
The value of the current through an inductance of $1H $ and of negligible resistance, when connected through an ac source of $ 200\, V $and $ 50\, Hz $, is
Question 19 :
What is the range between $f_1$ and $f_2$ of an RLC circuit that resonates at $150 kHz$ and has a Q of $30$?
Question 20 :
Assertion: In a series LCR circuit , at resonance condition power consumed by circuit is maximum .
Reason: At resonance condition , the effective resistance of circuit is maximum.
Question 21 :
The primary and secondary coils of a transformer have 50 and 1500 turns respectively. If the magnetic flux $\Phi$ linked with the primary coil is given by $\Phi$ = $\Phi _0$ + 4t, where $\Phi$ is in webers, t is time in seconds and $\Phi _0$ is a constant, the output voltage across the secondary coil is:
Question 22 :
Voltage and current in an A.C circuit are given by<br><br>$V=5sin\left ( 100\pi t-\dfrac{\pi }{6} \right )$ and <br><br>$I=4sin\left ( 100\pi t+\dfrac{\pi }{6} \right )$<br>
Question 23 :
A transformer converts 230 V A.C into 1035 V A.C. If the number of turns in the primary is 200, the number of turns in the secondary is :<br/>
Question 24 :
A source of 220V is applied in an A.C. circuit. The value of resistance is $220 \Omega$. Frequency & inductance are 50 Hz and 0.7 H, then wattless current is
Question 25 :
In a step up transformer, primary and secondary currents are $500\ A$ and  $100\ A$. The ratio of the number of turns in the respective coil is
Question 26 :
A 20V, 750 Hz source is connected to a series combination of R $=$ 100$\Omega $, C $=$ 10 $\mu F $ and  $L $=$ 0.1803  H$. Calculate the time in which resistance will get heated by $10^{o}$C. (If thermal capacity of the material $=$ 2 J / $^o$C )<br/>
Question 27 :
A RC series circuit of R$=15\Omega$ and $C=10\mu F$ is connected to $20$ volt DC supply for very long time. Then capacitor is disconnected from circuit and connected to inductor of $10$mH. Find amplitude of current.
Question 28 :
In a series LCR circuit $\mathrm{R}=200\ Omega$ and the voltage and the frequency of the main supply is $220$ $V$ and $50$ $Hz$ respectively. On taking out the capacitance from the circuit the current lags behind the voltage by $30^0$. On taking out the inductor from the circuit the current leads the voltage by $30^0$. The power dissipated in the LCR circuit is <br>
Question 29 :
A choke coil of resistance $5\Omega$ and inductance $0.6\space H$ is in series with a capacitance of $10\space \mu F$. If a voltage of $200\space V$ is applied and the frequency is adjusted to resonance, the current and voltage across the inductance and capacitance are $I_0, V_0$ and $V_1$ respectively. We have
Question 30 :
A series $LCR$ circuit containing a resistance of $120\space \Omega$ has angular resonance frequency $4\times10^5\space rad\space s^{-1}$. At resonance the voltages across resistance and inductance are $60\space V$ and $40\space V$, respectively. The value of inductance $L$ is
