Electricity and Magnetism-II Full Book MCQs

Q.1: Current increases in a coil, the induced current will be
         in the same direction
        in the opposite direction
        clockwise
        counterclockwise

Q.2: According to the lenz’s law, if you pull the magnet away the induced current will
change the pull
go with pull
oppose the pull
nothing

Q.3: According to lenz’s law, the direction of induced current in a conductor will be that which tends to produce which of the following effect?
        enhance the effect which produce it
        produce a greater heating effect
       produce the greater voltage
       oppose the effect which produces it

Q.4: Voltage can be induced in the wire by
            Moving the wire near a bar magnet
            Moving a magnet near the wire
            Changing the current in a nearby wire
            All of these

Q.5: When current decreases in a coil, the induced current will be
              In the same direction
             In the opposite direction
             Clockwise
             Counterclockwise

Q.6: Which of the following is not an application of lenz’s law ?
          Transformers
         AC generator
         A coil Traversed by AC current
        A DC motorQ.

7: Name the following law: a changing magnetic field creates an electric current in a coil
      Ampere’s law
      Fraday’s law
      lenz’s law
     Columbs law

Q.8: Name the following law: a moving magnet creates an opposing magnetic field
     Ampere’s law
    Faraday’s law
    lenz’s law
    columb’s law

Q.9: What face will be the loop face, if the north pole of magnet is moving towards the loop?
         North Pole
         South pole
         Face no any pole
        Both a and b

Q.10: Energy dissipates in loop having resistance R due to induced current is
         Mechanical power
         Electrical power
         Posse’s no power
         EMF

Lenz’s law derived a rule to find out the direction of:

Current induced in a circuit B). electromagnetic difference

Potential difference D) flow of power in fur

The direction of induced current always

Directs the cause B). oppose the cause

C). Remains the same as that of cause D) equal to cause that produces it

The direction of induced electromotive force (EMF) in a circuit is under the law of conservation of:

Mass B). energy C) charge D) momentum

The law that induced e.m.f and current always oppose the cause producing them is due to:

Faraday B). Coulomb C) Newton D) Lenz

An open coil has:

Zero resistance and inductance B). infinite resistance and zero inductance

C). Infinite resistance and neutral inductance D) zero resistance and high inductance

Lenz’s law decides the direction of:

EMF B). Magnet C) Charges D) Current

When North pole of bar magnet is moved towards the coil then direction of induced current is:

Upward B). Clockwise C) anticlockwise D) downward

When North pole of bar magnet is pulled out of coil then induced current is in which direction:

Clockwise B). Right C) Left D) anticlockwise

Lenz’s law introduced by Russian Physicist Heinrich Friedrich Emil Lenz in which year:

1804 B). 1834 C) 1865 D) 1850

Which of the folllwing is not an application of Lenz’s law:

Transformer B). AC generator C) A coil traversed by AC D) A DC motor

Answer Key:

1	2	3	4	5	6	7	8	9	10
A	B	B	D	B	D	C	A	B	D

The moving pendulum has energy?

Kinetic (b) Potential (c) Rotational (d) Solar

To and fro motion is called?

Oscillation (b) Vibration (c) Both (d) None

The overall energy in pendulum ?

Increases (b) Decreases (c) Remains constant (d) None

Electromagnetic energy can be stored in ?

Inductor (b) Capacitor (c) LC Oscillator (d) Battery

The variation of current and voltage in LC circuit gives which type of oscillation?

Magnetic (b) Electric (c) Electromagnetic (d) None

Energy stored in Capacitor is due to which field?

Magnetic (b) Electric (c) Electromagnetic (d) None

Energy stored in Inductor is due to which field?

Magnetic (b) Electric (c) Electromagnetic (d) None

The charge on Capacitor varies with time from?

Max. +ve to 0 (b) Max. –ve to 0 (c) Both (d) None

The reciprocal of time period is called?

Speed (b) Frequency (c) Energy (d) Oscillation

On which position potential energy is maximum?

Mean (b) Extreme (c) Both (d) None

1) Electromagnetic oscillation is a combination of

RC b. LC c. RLC

2) The average energy in electormagnetic oscillation will be

Same b. different c. conserved

3) The capacitor and inductor are connected

series b. parallel c. non of them

4) Energy stored in capacitor

Ue= b. Ue= c. Ue=

5) Energy stored in inductor

Um= b. Um= c. Um=

6) Charge in capacitor w.r.t time

Same b. increase c. decrease

7) The angular and linear frequency ar related as

b. c.

8) Ue=??

qwt/2C b. qwt/3C c. qwt/4t

9) Um=??

qwt/2C b. qwt/3C c. qwt/4t

10) The magnetic and electrical energy are

inversely prop. b. directly prop. c. constant

1. An oscillation that fades away with time is

(a) Simple Harmonic motion. (b)Damped Oscillation

2. Resister-Inductor-Capacitor is an example of;

(a) Damped Oscillation. (b) simple Harmonic motion

3. The electromagnetic energy is dissipated as energy due to damping

Oscillqti)on.

(a) Electric Energy. (b) Magnetic Energy (c) Nuclear Energy. (d) Thermal Energy

4. The total electromagnetic energy of the damped oscillation is

(a) U = q²/2C + 1/2 LI². (b) U = q²/2C + 1/2LI

5. The rate of transfer of electromagnetic energy to thermal energy is

(a) du/dt = IR². (b) du/dt = – IR² (c) du/dt = -I²R. (d) du/dt = I²R

6. The equation of motion of damped oscillator is;

(a) L d²q/dt² + R dq/dt + q²/c = 0 (b) L dq/dt + R dq²/dt² + q/c = 0

7. The electrical energy stored in the electric field of a capacitor is;

(a)Ue = q ²/2c e^-Rt/L Cos(w`t + O) (b) Ue = q ²/2c e^-Rt/L Cos²( w`t + O)

(d) none of these

8. The frequency at which a system tends to oscillate in the ansence of any driving or damping force is known as ;

(a) Natural frequency. (b) Artifical frequency

9. The formula of natural frequency of electromagnetic oscillation is;

(a) w = √LC (b) w = √L/C (c) w =√ C/L (d) w = 1/√LC

10. When an oscillating systemis driven by a periodic force that is external to the oscillating system, is called

(a) Simple Harmonic motion. (b)Damped Oscillation

11. The relationship between resonance and damping is;

(a) Direct. (b) inverse. (c) opposite. (d) none of these

12. If the damping of a system is less, the amplitude will be

(a) high. (b) low. (c) same. (d) Constant

1.The current produced by alternating EMF is known as

(a)A.C. (b)D.C. (c)E.P. (d)none

2.The A.C generator consist of major parts:

(a) 3 ( b) 5 (c) 4 (d) 2

3.The most common source of A.C

(a) Motor (b) Battery (c) generator (d) soular cell

4.The frequency of A.C source used in Pakistan:

(a) 50Hz (b) 60Hz (c) 45Hz (d) 70Hz

5.Commutator was invented by

(a) Henry (b) Oersted (c) williamsurgeon (d) Maxwell

6.Which one of the following is not present in A.C. generatoe?

(a) Armature (b) Magnet (c) slipring (d) commutator

7. Induced emf in A.C. generator can be increased by:

(a) Decreasing area. (b) Decreasing Magnetic field

(c) Increasing area of coil (d) slowing down speed of coil

8. Commutator was invented in:

9.The principle of A.C. generator is based on

(a) Couloub’s law (b) Ampere’s law (c) Farady’s law (d) Lenzis law

10.A device which convert electrical energy into mechanical energy is called:

(a) Transformer (b) A.C generator (c) D.C generator (d) none

Topic transformer

Q 1 multiple choice questions

1 ) the laminations of a transfer are there to

a) to increase impedance b) reduce transients c) reduce eddy current d) increas the transformation rates

2) A transformer steps up the voltage by a factor of 100 the ratio of current in primary to that of secondary is

a) 1 b) 100 c) 0.01 d) 0.1

3) An ideal transformer does not change

a) voltage b) power c) current d) none

4) the frequency of the voltage at the secondary of a transformer is

a) greater than that of primary b) less than that of primary c) equal to that of primary d) none of these

5) the basic function of transformer is to change

a) level of voltage b) power level c) power factor d) frequency

6) when a transformer is operating on an load the primary voltage approximately balanced by

a) primary induced emf b) secondary induced emf c) terminal voltage across secondary d) voltage drop across the reactance and resistance

7) An open circuit test on a transformer is performed basically to determine

a) copper loss b) iron loss c) leakage impedance d) regulation

8) the copper loss of transformer at half load is measured as 400,then the copper loss at full load will be

a) 800w b) 200w c) 400 d) 1600w

9) the transformer core is laminated

a) because it is difficult to fabricate solid core

b) because laminate core provide high flux density

c) to reduce eddy current loss

d) to increase main flux

10) flux in transformer are

a) increase with load b) decrease with load c) remains constant d) none

11) efficiency of transformer is maximum in

a) transformer is unloaded b) copper loss is equal iron loss c) eddy current are equal to iron loss d) none

12) if the supply transformer is double then

a) hestersis loss is double b) eddy current loss also double c) iron loss double d) copper loss double

13) open circuit test in a transformer is performed with

a) rates transformer voltage b) rates transformer current c) direct current d) high frequency supply

14) the core of transformer M made of

a) annealed copper b) silicon steel

c) succeed wood d) aluminum

15) if the full load iron iron loss of transformer is 100w what will be it’s iron at half load

a) 100w b) 200w c) 150w d) 25w

16) the number of turns in the primary winding of a transformer depend on

a) input voltage b) input current c) both a and b d) none of these

17) in a transformer electrical power is transformed from one circuit to an other with out change in

a) voltage b) current c) frequency d) turns

18) the two winding of transformer are designed

a) primary and secondary winding

b) primary and HV winding

c) HV and LV winding

d) secondary and LV winding

19) the transformer used for Acha welding sets is

a) booster type b) step up type c) step down type d) equal turn type

20) in case of power transformer , the no load current in turn of rated current is

a) 10 to 20% b) 2 to 6 % c) 15 to 20% d) 30 to 50%

Answers key

1) c 2) c 3) c 4) c 5) a 6) a 7) b 8) d 9) c 10) c 11) b 12) a 13) a 14) b 15) a 16) a 17) c 18) a 19) c 20) b

1. The instantaneous rate at which energy is dissipated is called

a)phasor b)resistance c) dissipaion power

2.Voltage and current has been assumed to be constant which thing is constant

a)polarity b)voltage c)resistane

3.Resistance which is connected with AC generator having emf

a)EcosØt b)Eosinwt c)Esinwt

4.Angular speed,length,projection,rotation among them which possess following properties

a)ohm’s law b)phasor law c)phasor reactor

5.Root mean square value of voltage

a)Io/(2)^1/2 b)Vo/(2)^1/2 c)none

6.Power dissipation is equal to

a)p=Rsin^2(wt= Ø ) b)Rcos^2(wt= Ø c)none

7.The circuit current and voltage in AC circuit are generally by allotting maximum

a)DCmotor b)coil c)root mean square

8.Phasor diagram of AC and voltage is

a)time b)displacement c)current d)resistane

9.The current in the resistace

a)Ir=Vo/Rsinwt b)Ir=VoRcoswt c)none of there

10.The oscillating shape of Ac supply in circuit analysis is

a) transverse wave b)sinusoidal wave c)longitudinal wave

1	The polarity of D.C current remains	A ) Constant B ) Zero C ) Variable D ) A&B
2	The Oscillating shape of an AC supply	A) Sinusoidal Waveform B)Traditional waves C ) Mechanical waves D ) None
3	The amplitude of the alternating voltage across resistance is	A ) Not equal B ) Equal C ) Different C) All of these
4	The current through resistance is given as	A ) Iv = IovSin(wt-Φ) B) IV = IovSinΦ C ) IovSin(wt-Φ) D) None
5	The time varying quantities such as voltage and current can be represented by	A ) Torque B ) Projection C ) Momentum D ) Phasors
6	The Phasor is a ______ Quntity	A ) Scalar B) Vector C ) Both D) None
7	Which is a property of Phasor Vector	A ) Length B ) Projection C ) Both A&B D ) None
8	SI Unit of resistance is	A )Watt B )Voltage C ) Ohm D)Newton
9	The instantaneous rate at which energy is dissipated in a resistance is given as	A )Power Dissipation B ) Resistance C ) Current D ) voltage
X	The average rate at which energy is dissipated in a resistor is given as	A ) (Ivms)² B ) (Ivms)^R C ) (Irms)²xR D ) (Ims)²

Instantaneous voltage across pure inductor _______ the current

Lag b) lead c) both

Angle between and is

180 b) 270 c) 90

Instantaneous voltage across pure resistor is ______ with current

increase b) out of phase c) In phase

RLC circuit connected in series with __________

solar cells b) DC voltage c) AC voltage

In RLC series circuit I and VR

increase b) out of phase c) In phase

6) In RLC series circuit source voltage = _______

a) ( +) – b) ( -) + c) ( -) +

7) The non resistive component of impedance

capacitance b) inductor c) reactance

8) Z=??

b) c) I+Vs

9) If < then angle will be

+90 b) 270 c) -90

10) Unit of impedance is

Henery b) ohm c) candela

Resonance Frequency In RLC Series Circuit

Why inductive reactance and capacitive reactance cancel each other?

90cᵒ apart each other b. 180cᵒ apart each other

60cᵒ apart each other

What is the natural frequency of RLC series circuit?

F=1/2 π [LC]^1/2

F₀₌₁₂ π√1LC

None of these

The impedance of RLC series circuit at resonance is:

Z=R b. Z=R^⅓ c. Z=R ^⅔

The current amplitude is given as at resonance:

Io=Ls/R b. Io=2Vs/R c. Io=Vs/R

Phase relationship between current and voltage:

φ= b. φ= c. None of these

Phase relationship between current and voltage at resonance: I know

Φ=⅓ b. Φ=0 c. Φ=π/3

When the inductive reactance and capacitance reactance are equal in magnitude _________ occurs.

RLC parallel circuit b. RC circuit

c. resonance of RLC series circuit

The current amplitude is given as:

lo= Vs/ [ R²+ (XL² -XC²)]^1/2 b. lo= Vs/ [ R²– (XL² +XC²)]^1/2

What is the formula of inductive reactance?

XC=WL b. XC=1/WC c. XL=WL

Answer key:
1	b	6	b
2	a	7	a
3	a	8	c
4	c	9	a
5	a	10	c

Resonance frequency in series RLC circuit

1. In a series RLC circuit, the phase difference between the current in the capacitor and the current in the resistor is?

a) 0^o

b) 90^o

c) 180^o

d) 360^o

2. In a series RLC circuit, the phase difference between the current in the inductor and the current in the resistor is?

a) 0^o

b) 90^o

c) 180^o

d) 360^o

3. In a series RLC circuit, the phase difference between the current in the capacitor and the current in the inductor is?

a) 0^o

b) 90^o

c) 180^o

d) 360^o

4. In a series RLC circuit, the phase difference between the current in the circuit and the voltage across the resistor is?

a) 0^o

b) 90^o

c) 180^o

d) 360^o

5. In a series RLC circuit, the phase difference between the current in the circuit and the voltage across the capacitor is?

a) 0^o

b) 90^o

c) 180^o

d) 360^o

6. _________ the resonant frequency, the current in the inductor lags the voltage in a series RLC circuit.

a) Above

b) Below

c) Equal to

d) Depends on the circuit

7. _________ the resonant frequency, the current in the capacitor leads the voltage in a series RLC circuit.

a) Above

b) Below

c) Equal to

d) Depends on the circuit

8. The circuit is said to be in resonance if the current is ____ with the applied voltage.

a) in phase

b) out of phase

c) 45⁰ out of phase

d) 90⁰ out of phase

9. In a series resonance circuit, series resonance occurs when?

a) XL = 1

b) XC = 1

c) XL = XC

d) XL = -XC

10. As XL = XC in a series resonance circuit, the impedance is_________

a) purely capacitive

b) purely inductive

c) purely resistive

d) capacitive and inductive

11. At resonant frequency, the voltage across capacitor is _______ the voltage across inductor.

a) greater than

b) less than

c) greater than or equal to

d) equal to

12. In series RLC circuit, the voltage across capacitor and inductor are ______ with each other.

a) in phase

b) 180⁰ out of phase

c) 90⁰ out of phase

d) 45⁰ out of phase

13. The voltage across the LC combination in a series RLC circuit is?

a) 0

b) 1

c) 2

d) 3

14. The expression of resonant frequency in a series resonant circuit is?

a) 1/(2π√C)

b) 1/( 2π√L)

c) 2π√LC

d) 1/(2π√LC)

Answer key

1	2	3	4	5	6	7
a	a	a	a	b	a	b
8	9	10	11	12	13	14
a	c	c	d	b	a	d

(1)Galvanometer shows zero deflection when…current flow to coil

(a)zero(b)maximum (c)steady current (d)unsteady current

(2)Magnetic field experience force

(a)f=gv.B (b)F=gv×B (c)a&b (d)F=qvB

(3)when motor is just started back emf is also….

(a)maximum (b)minimum (c)zero (d) All of

(4) which condition setup setpdown transfer

(a) NSgreatrNP and VS >VP (b)NS<NP (c)Both and b (d)vs greater VP

(5)Induced currunt depends upon…given concept I=E/R

(a) emf (b) back emf (c)Resistance (d)capacitance

(6)which relation VS1/A called

(a)selfinductance (b)Henry (c)Hertz (d)mutual current

(7) According to electromagnetic induction concept lens law farbits the following current

(a) direct current (b) slow current (c) Induced current

(8)which material Greeks use as a magnetic material

(a)SO4 (b)Feos (c)Fe (d)Fe3O4

(9)Where the magnetic is strongiest in magnet

(a)in middle (b)at end (c)both a &b (d)remain same

(10)What is the use of magnetic field in 11^th century

(a) Navigation (b)discovery (c)for current (d) voltage

1. What is the value of permeability of free space or perme?

A) 4π*10^-7Hm^-2 ©B) 4π*10^-7Hm^-1

C) 4π*10^-7m^-2 D) 4π*10^-7 Nm

2.The measure of the ability of a material to support the

formation of a magnetic feild with in itself.

©A) permeability B) Magnetic susceptibility

C)Magnetization D) Magnetic intensity

3.when william Gilbert first proposed that the earth itself

is a magnet.

A) 1500 ©B) 1600

C) 1700. D)1800

4.where the magnetic effect is strongest in a magnet.

A) in middle ©B) at ends

C) both a and b. D) remain same

5.What is the use of magnet in eleventh century.

©A) navigation. B) discovery

C) for current D) Voltage

6. Which material Greeks used as a magnetic material.

A)SO4. B) Feos

C) Fe ©D) Fe3O4

7. What is the unit of magnetic dipole moment.

A) Nm^2 B) Am

©C) Am^2 D) Nm

8. Term magnet come from ancient Greek city of……………

at which many nuetral magnets were found.

A) indonesia B) malaisia

©C) magnesia D) both a and b

9. The space surrounding the magnet upto which its

Influence felt is khown as………………

©A) magnetic field B) electric field

C) strong field D) weak field

10. A magnet has poles…………… .

A) 1 © B) 2

C) 3 D) 4

1. Inductor like capictor store energy………

a) temporary b) permanent c) None d) both a and b

2. Inductor store energy in ………

a) Electric field b) Magnetic field c) electric and magnetic fields d) None

3. Inductance is measured in

a) Joule b) Columb c) Henry d) Newton

4. ……..is a measure of intensity of Magnatic Field.

a) Joule b) Columb c) Henry d) Newton

5. When current is decrease from ” I ” to ” 0″ then energy in capictor will…..

a) store b) increase c) Released d) both a and b

6. When current is steady ….

a) No EMF b) No current c) None d) both a and b

7. Inductor are simply…..

a) wire b) coil of wire c) chip of iron d) None

8. When the source of electron removed then Magnetic field

a) Produced b) Collapse c) decrease d) increase

9. Inductor can be wound in

a) straight line b) circular form c) zig zag form d ) both c and d

10. If current is increase from 0 to ” I ” , source has to work against ….

a) voltage b) Induced EMF c) EMF d) None

Q. 1 Choice the right answer.

1. In RL-series circuit the indicator will connect in ………………. with resistor.

A. parallel

B. series

C. May parallel or series

D. none

2. RL-series circuit is connected a ………. voltage.

A. high

B. low

C. constant

D. variable

3. The current flow through the circuit can not rise rapidly to

A. zero

B. constant

C. minimum

D. maximum

4. The magnetic flux through indicator in RL series circuit is induce due to

A. self induced emf

B. high voltage

C. high resistance

D. all above

5. In RL series circuit the field is reduce to zero when flow of current become

A. zero

B. constant

C. Minimum

D. maximum

6. The source of voltage is connected in ……….. with RL series circuit

A. series

B. parallel

C. may parallel or series

D. none

7. In RL series circuit the field is reduce to ……. when current become constant.

A. zero

B. constant

C. minimum

D. maximum

8. What is the potential difference across inductor in RL series circuit

A. E e^-Rt/L

B. -E e^-Rt/L

C. E e^Rt/L

D. – E e^Rt/L

9. What is the potential difference across the resistor in RL series circuit

A. E e^Rt/L

B. -E e^Rt/L

C. -E e^-Rt/L

D. E e^-Rt/L

10. In RL series circuit the resistor in connected in ………. with inductor.

A. series

B. parallel

C. may parallel or series

D. none

A transformer can not raise or lower the voltage of a D.C supply because

(a)there is no need to change the D.C voltage (b) A D.C circuit has more losses

(c)Faraday’s law of electromagnetic inductions are not valid since the rate of change of flux is zero (d) None of the above Ans=C

(2) A Power transformer transforms

(a) Voltage (b) Current (c) Power (d) Frequency Ans=A

(3) Which of the following is not a part of transformer installation?

(a) Conservator (b) breather (c) Buchholz relay (d) exciter Ans=A

(4) In a transformer the energy is conveyed from primary to secondary

(a) through cooling coil (b) through air (c) by the flux (d) None of the above Ans=C

(5) The path of a magnetic flux in a transformer should have

(a) high resistance (b) high reluctance (c) low resistance (d) low reluctance Ans=d

(6) Sumpner’s test is conducted on transformers to determine

(a) temperature (b) stray losses (c) all-day efficiency (d) none of the above Ans=A

(7) The dielectric strength of transformer oil is expected to be

(a) 11kV (b) 33kV (c) 100kV (d)330kV Ans=b

(8) While conducting short-circuit test on a transformer the following side Is short-circuited

high voltage side (b)low voltage side (c) Primary side (d) Secondary side Ans=b

(9) Primary winding of a transformer

(a) is always a low voltage winding (b) is always a high voltage winding (c) could either

Be a low voltage or high voltage winding (d) None of the above Ans=C

(10) The degree of mechanical vibrations produced by the lamination of a transformer depends on

tightness of clamping (b) gauge of laminations (c) size of laminations

(d) all of the above Ans=d

1. To increase the current in a series RL circuit, the frequency

should be constant

should be decreased

should be increased

cannot be determined without values

2. When the resistor voltage in a series RL circuit becomes less than the inductor voltage, the phase angle

cannot be determined

increases

decreases

is not affected

3. If the frequency is halved and the resistance is doubled, the impedance of a series RL circuit

A) cannot be determined without values

B) remains constant

C) halves

D) doubles

4. When the frequency is decreased, the impedance of a parallel RL circuit

is not a factor

remains constant

decreases

increases

5. When the frequency of the voltage applied to a series RL circuit is increased, the phase angle

decreases

increases

does not change

cannot be determined without values

6. To increase the current in a series RL circuit the frequency

Should be increase

Should be decreased

Should be constant

Cannot be determined without values

7. In RL series circuit the resistor is connected in with indicator

series

Parallel

May parallel or series

None

8. The current flow through the circuit can not rise rapidly to

Zero

Constant

Minimum

Maximum

9. In RL-series circuit is connected a voltage

Highr

Low

Constant

Variable

10)In RL series circuit the field is reduce to when current became constant

Zero

Constant

Minimum

Maximum

1.Source of EMF in RLC circuit is

a) Battery b) Rheostat

b) Electrical d) Magnetic energy

Ans: Electrical energy

2. Capacitive element store energy in

a) Electrical field b) Battery

c) Magnetic field c) Capacitor

Ans : Electric field

3. RLC Series circuit can follow the

a) Law of force

b) Law of conservation

c) Law of dynamic

d) Law of conservation of energy

Ans: Law of conservation of energy

4. Power dissipation should be_____ in capacitive and inductive

element

a) zero b)100o

b) 180o

d) 90o

Ans; zero

5. Inductive element store energy

a) Rheostat b) Inductive

c) Magnetic field d) Battery

Ans; Magnetic field

6. At resonance the value cos

a) 1°

b) 0°

c) 90°

d) 80°

Ans; 1°

7. Root mean square voltage is

a) Vrms=vo I/ √2

b) vrms=Vo/ √2

c) Vrms=RI/ √2

d) Vrms=Io/ √2

Ans; vrms=Vo/ √2

8. Root mean square current is

a) Irms=vo I/ √2

b) Irms==Io/ =Vo/ √2

c) Irms=RI/= √2

d) Irms=Io/ √2

Ans; Irms= Io/ √2

9. The instantaneous voltage across a pour inductor vL leads the

current by

a) 180°

b) 90°

c) 0°

d) 160o

Ans; 90o

10. In resistive element there is a phase difference of

a) 180o

b) 90o

c) 0

d) No

Ans; no

11. The average energy in capacitive element remain

a) 90

b) Variable

c) Zero

d) Constant

Ans; constant

12. In RLC series circuit, if the voltage across capacitor is greater

than voltage across inductor, then power factor of the network is

a) Lagging b) leading

c) Unity d) zero

Ans; leading

13. Average power taken by a pour capacitor is

a) Zero

b) Minimum

c) Maximum

c) All

Ans; zero

14. The resistivity of the conductor depends on

a) Area of the conductor

b) Length of the conductor

c) Type of the material

d) None of these

Ans; Types of the material

15. To obtain a high value of capacitance, the permittivity of

dielectric medium should be

a) Low

b) Zero

c) High

d) Unity

Ans; High

16. In series RLC circuit what is the power factor just above the

resonance frequency

a) Lagging

b) Leading

c) Unity

d) Zero

Ans; lagging

17. In series RLC circuit what is the power factor just below the

resonance frequency

a) Lagging

b) Leading

c) Unity

d) Zero

Ans; leading

18. In RLC series circuit at resonance condition the value of

current is

a) Maximum

b) Minimum

c) Zero

d) None of above

Ans; Maximum