Alternating Current Applied to an Inductor

Q. 36.A rectangular surface of sides 10cm and 15cm is placed in a uniform electric field of 25 V/m, such that the surface makes an angle of 30 degree with the direction of electric field. Find the flux of electric field through the rectangular surface

Q. A condensor of capacity C is charged to a potential difference of V1 .The plates of the condensor are then connected to an ideal inductor L. The current through the inductor when the potential difference across the condenser reduces to V2 is

Q. Derive the expression for the electric field of a semi infinite wire ??

Q. An inductive circuit contains a resistance of 10 ohm and an inductance of 2.0 henry. If an ac voltage of 120 volt and frequency of 60 Hz is applied to this circuit, the current in the circuit would be nearly

1. 0.32 amp
2. 0.16 amp
3. 0.80 amp
4. 0.48 amp

Q. Power factor of an $L-R$ series circuit is $0.6$ and that of a $C–R$ series circuit is $0.5$. If the elements $(L,C,$ and $R)$ of the two circuits are joined in series, the power factor of this circuit is found to be $1$. The ratio of the resistance in the $L-R$ circuit to the resistance in the $C-R$ circuit is

1. $\frac{6}{5}$
2. $\frac{3\sqrt{3}}{4}$
3. $\frac{5}{6}$
4. $\frac{4}{3\sqrt{3}}$

Q. An inductor and a resistor are connected in series with an AC source. In this circuit

1. current and potential difference across the resistor lead the potential difference across the inductor.
2. current and potential difference across the resistor lag behind the potential difference across the inductor by an angle $\frac{\pi }{2}$.
3. current and potential difference across the resistor lag behind the potential difference across the inductor by an angle $\pi$.
4. potential difference across the resistor lags behind the potential difference across the inductor by an angle $\frac{\pi }{2}$ but the current in the resistor leads the potential difference across the inductor by an angle $\frac{\pi }{2}$.

Q. The device that can act as a complete electronic circuit is

1. Junction diode
2. Integrated circuit
3. Junction transisto
4. Zener diode

Q. Explain, with the help of a circuit diagram, the working of a p-n junction diode as a half-wave rectifier.

Q. Potentiometer wire of length 1m is connected inseries with 490 ohmresistance and 2V battery. If0.2mV cm-lis the potential gradient, thenresistance of the potentiometer wire is

Q. An alternating voltage is connected in series with a resistance R and an inductance L If the potential drop across the resistance is 200 V and across the inductance is 150 V, then the applied voltage is

1. 350 V
2. 250 V
3. 500 V
4. 300 V

Q. A 20 volts ac is applied to a circuit consisting of a resistance and a coil with negligible resistance. If the voltage across the resistance is 12 V, the voltage across the coil is

1. 10 volts
2. 16 volts
3. 8 volts
4. 6 volts

Q.

What does infinite resistance mean in circuit.

Ideally we have zero resistance does that mean that if I apply an potential difference V, it will come to zero (because of ohm law)

V=IR

BUT R=0

V=0

Q.

An inductor of 30 mH is connected to a 220 V, 100 Hz ac source. What will be the inductive reactance?

Q.

The phase relationship between current and voltage in a purely resistive circuit is best represented by.

1. 

2. 

3. 

4. 

Q. A coil of inductance $1\text{H}$ and resistance $100\Omega$ is connected to a battery of $6\text{V}$. Determine approximately:
(a) The time elapsed before the current acquires half of its steady - state value.
(b) The energy stored in the magnetic field associated with the coil at an instant $15\text{ms}$ after the circuit is switched on. (Given $\ln 2=0.693,e^{-3/2}=0.25$)

Q. A $220V$ input is supplied to a transformer. The output circuit draws a current of $2.0A$ at $440$ volts. If the efficiency of the transformer is 80%, the current drawn by the primary winding of the transformer is

1. 3.6 ampere
2. 2.8 ampere
3. 2.5 ampere
4. 5.0 ampere

Q. An inductive circuit contains resistance of 10 Ω and an inductance of 20 H. If an ac voltage of 120 V and frequency 60 Hz is applied to this circuit, the current would be nearly

1. 0.016 amp
2. 0.48 amp
3. 0.80 amp
4. 0.32 amp

Q. Choke coil works on the principle of

1. Transient current
2. Self induction
3. Mutual induction
4. Wattless current

Q.

A source of constant voltage $V$ is connected to a resistance $R$ and two ideal inductors $L_1$ and $L_2$ through a switch $S$ as shown. There is no mutual inductance between the two inductors. The switch $S$ is initially open. At $t=0$, the switch is closed and current begins to flow. Which of the following options is/are correct?

1. At $t=0$, the current through the resistance $R$ is $\frac{V}{R}$

2. After a long time, the current through $L_2$ will be $\frac{V}{R}\frac{L_1}{L_1+L_2}$

3. After a long time, the current through $L_1$ will be $\frac{V}{R}\frac{L_2}{L_1+L_2}$

4. The ratio of the currents through $L_1$ and $L_2$ is fixed at all times $(t>0)$

Q. when the electric flux is positive and negative?

Q.

A $LCR$circuit behaves like a damped harmonic oscillator. Comparing it with a physical spring-mass damped oscillator having damping constant $b$, the correct equivalence will be

1. $L\leftrightarrow \frac{1}{b},C\leftrightarrow 1/m,R\leftrightarrow \frac{1}{k}$

2. 

3. $L\leftrightarrow m,C\leftrightarrow k,R\leftrightarrow b$

4. 

Q. What is instantaneous current

Q.

Explain why transformer is the most efficient electrical machine?

Q. the coefficient of self induction of two inductor coils arew 20 mH and 40 mH respectively.if the coils are connected in series so as to support each other and the resul†an t induc†an ce is 80 mH then the value of mutual induc†an ce between the coils willbe 1. 5 mH 2.10 mH3.20 mH4.40 mH

Q.

Which types of losses do not occur in the transformer?

1. Iron losses

2. Copper losses

3. Mechanical losses

4. Flux leakage

Q. When an AC source is connected across a pure resistor, the current in the resistor -

1. lags behind the voltage.
2. is in phase with the voltage.
3. leads ahead the voltage.
4. may lead or lag the voltage.

Q.

In pure inductive circuit, the curves between frequency f and reciprocal of inductive reactance 1/X_L is

1. 
   

2. 
   

3. 
   

4. 
   

Q. A $220V,50HzAC$ source is connected to a $25V,5W$ lamp and an additional resistance $R$ in series (as shown in figure) to run the lamp at its peak brightness, then the value of $R$ (in ohm) will be _____.

Q. A solenoid having a core of cross section 4 cm square half air and half iron (relative permeability is equal to 500) is 22 cm long if the number of turns on it is 10 power 3 its self inductance is

Q. what is electricity