Question 1 :
A transformer steps up an $$AC$$supply from$$220 V$$to$$2200V$$. If the secondary coil of the transformer has$$2000$$turns, the number of turns in its primary coil will be:
Question 2 :
A step down transformer changes the high input voltage used in our houses $$(120V)$$ into the low voltage used to charge an electric razor $$(24V)$$. What must be the ratio of the turns of wire from the primary side of the transformer to the secondary side?
Question 4 :
A transformer connected to $$220$$ volt line shows an output of $$2A$$ at $$11000V$$. The efficiency is $$100$$%. The current drawn from the line is:
Question 5 :
Match the following<br/>a) step up transformer     d) turns ratio is 1<br/>b) step down transformer e) Ns > Np<br/>c) Ideal transformer           f) Np > Ns<br/>
Question 7 :
In a $$LC$$ circuit. Angular frequency at resonance is $$w$$. What will be the new angular frequency when inductor's introduces is made $$2$$ times and capacitance is made $$4$$ times?
Question 8 :
The ratio between the primary voltage and the secondary voltage in a transformer is equal to:<br/>
Question 10 :
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 11 :
An ideal transformer has 400 turns in the primary and 200 turns in the secondary. If the primary is connected to a 12 V battery, then the secondary voltage is<br/>
Question 12 :
A step-down transformer reduces the voltage of a transmission line from $$2200\ V$$ to $$220\ V$$. The power delivered by it is $$880\ W$$ and its efficiency is $$88$$%. The input current is :
Question 13 :
What do we name the  device which increases the emf ?<br/>
Question 14 :
In a step-up transformer, the number of turns in the primary are .................. than the number turns in the secondary.
Question 16 :
The primary of a transformer has $$400$$ turns while the secondary has $$2000$$ turns. If the power output from the secondary at $$1000V$$ is $$12kW$$, what is the primary voltage?
Question 17 :
In an ideal parallel LC circuit, the capacitor is charged by connecting it to a DC source which is then disconnected. The current in the circuit
Question 19 :
If the resistance in a parallel resonant circuit is reduced, the bandwidth:
Question 20 :
A step up transformer converts $$100$$ V at primary to $$300$$ V at secondary.  If the primary current is $$6$$A, then the secondary current is ______A
Question 21 :
The current and voltage in AC circuit are given by<br>$$ l = 5 \sin \left( 100 t - \dfrac {\pi}{2} \right) A $$ and $$ V = 200 \sin ( 100 t ) $$ volt. <br>The power dissipated in the circuit will be :
Question 22 :
In a transformer, the number of turns of primary coiland secondary coil are 5 and 4 respectively. If 220V is applied on the primary coil, then the ratio ofprimary current to the secondary current is :
Question 23 :
The power loss in an $$AC$$ circuit is $$E_{rms}$$ $$I_{rms}$$, when in the circuit there is only
Question 24 :
Assertion (A): More the turns more is the<br>resistance<br>Reason(R): Impedance of primary and secondary<br>in a transformer is directly proportional to number<br>of turns in the coils.<br><br>
Question 25 :
For L-C-R, A.C circuit resonance frequency is $$600Hz$$ and frequencies at half power points are $$550Hz$$ and $$650Hz$$. What will be the Q-factor?
Question 26 :
Thesharpness of resonance in a series $$L-C-R$$ resonantcircuit,as the resistance of the circuit is increased,goeson
Question 27 :
In a transformer, the number of turns of primary coil and secondary coil are $$5$$and$$4$$respectively. If$$220 V$$isapplied on the primary coil, then the ratioof primary current to the secondary current is
Question 29 :
The primary and secondary coils of a transformer<br>have 50 and 1500 turns respectively. If the<br>magnetic flux linked with the primary coil is<br>given by $$\phi =\phi _{0}+4t,$$ where $$\phi$$ is in webers, t is<br>time in seconds and $$\phi_{0}$$ is a constant, the output<br>voltage across the secondary coil is:<br><br><br><br><br><br>
Question 30 :
A circuit has a self-inductance of $$1H$$ and carries a current of $$2A$$. To prevent sparking, when the circuit is switched off, a capacitor which can withstand $$400\ V$$ is used. The least capacitance of the capacitor connected across the switch must be equal to
Question 31 :
Assertion: A step up transformer can also be used as a step down transformer.
Reason: This is because $$\cfrac { { E }_{ p } }{ { E }_{ s } } =\cfrac { { n }_{ s } }{ { n }_{ p } } $$
Question 32 :
The ratio of the secondary to the primary turns in a transformer is $$3:2$$ and the output power is $$P$$. Neglecting all power losses, the input power must be:<span class="_wysihtml5-temp">
Question 33 :
The correct formula for the angular frequency $$\omega_0$$ of an $$L-C$$ resonant circuit is
Question 34 :
An alternating voltage frequency $$\omega$$ is induced in electric circuit consisting of an inductance $$L$$ and capacitance $$C$$, connected in parallel. Then across the inductance coil the<br>(i) current is maximum when $${\omega}^{2}=1/(LC)$$<br>(ii) current is minimum when$${\omega}^{2}=1/(LC)$$<br>(iii) voltage is minimum when$${\omega}^{2}=1/(LC)$$<br>(iv) voltage is maximum when$${\omega}^{2}=1/(LC)$$
Question 36 :
In a transformer the output current and voltage are $$4 A$$and$$20 V$$respectively. If the ratio of number ofturns inthe primary and secondary coil is$$2 : 1$$respectively, what isthe input current and voltage?
Question 37 :
What would be the Q factor for a purely inductive circuit?
Question 38 : <p>Turn ratio in a setup transformer is 1: 2.If a lechlanche cell of 1.5 V is connected across the input, what is the voltage across the output?</p>
Question 39 :
An inductance, a capacitance and a resistance are connected in series across a source of alternating voltages. At resonance, the applied voltage and the current flowing through the circuit will have a phase difference of<br/>
Question 40 :
A transformer having $$4000$$ turns on its primary side and $$500$$ turns on the secondary side. If the input voltage is $$240\ V$$, find out the output voltage of the secondary side of the transformer ?
Question 41 :
A capacitor of capacitance $$1\space \mu F$$ is charged to a potential of $$1\space V$$. It is connected in parallel to an indicator of inductance $$10^{-3}\space H$$. The maximum current that will flow in the circuit has the value
Question 42 :
A power transformer is used to set up an alternating emf of $$220V$$ to $$4.4kV$$ to transmit $$6.6kW$$ of power. The primary coil has $$1000$$ turns. What is current rating of secondary? (Assume efficiency 100%)
Question 43 :
Assertion : In series LCR circuit, the resonance occurs at one frequency only.<br/>Reason  : At resonance the inductive reactance is equal and opposite to the capacitive reactance.<br/>
Question 44 :
A series resonant circuit contains $$L = \dfrac{5}{\pi} mH, C = \dfrac{200}{\pi} \mu F$$ and $$R = 100 \mu$$. If a source of emf $$e = 200 sin 1000 \pi t$$ is applied, then the rms current is:
Question 45 :
The ratio of no. of coils in the secondary to primary  step up transformer is $$4:1$$. If a current of $$4\ $$$$A$$ is applied to the primary, the current in secondary will be:
Question 46 :
In an AC circuit $$V$$ and $$I$$ are given $$V=100\sin { \left( 100t \right)  } V$$ and $$I=100\sin { \left( 100 t+\pi/3 \right)  } mm$$. The power dissipated in the circuit is:
Question 48 :
In a step-up transformer the voltage in the primary is 220 v and the voltage is found to be 22000 v. The current in the secondary ( neglect losses)m is
Question 49 :
In an LCR circuit having $$L=8.0H,C-0.5\mu F$$ and $$R=100\Omega$$ in series, the resonance frequency is:
Question 50 :
A coil of inductance $$L$$ has an inductive reactance of $$ X_L $$ in an AC circuit in which the effective current is $$I$$. The coil is made from a super-conducting material and has no resistance. The rate at whichpower is dissipated in the coil is
