## Electric circuits one mark Questions

1. The “Superposition theorem” is essentially based on the concept of
A. duality
B. linearity
C. reciprocity
D. non-linearity

1. Cells are connected in parallel in order to
1. increase the voltage available.
2. reduce cost of wiring.
3. increase the current available.
4. reduce the time required to fully charge them after use

1. The power factor of a purely resistive circuit is
1. zero.
2. unity.
3. lagging.

1. The power taken by a 3-phase load is given by the expression
1. 3VL IL cos f .
2. 3 VL IL sin f .
3. 3 VL IL cos f .
4. 3 VL IL sin f .

1. Which of the following generating stations has the minimum running cost
1. hydro-electric station.
2. nuclear power station.
3. thermal power station.
4. diesel power plant.

1. Which of the following motors has a high starting torque?
1. ac series motor.
2. dc series motor.
3. induction motor.
4. synchronous motor.

1. The effect of increasing the length of the air gap in an induction motor will be to increase
1. power factor.
2. speed.
3. magnetising current.
4. air-gap flux.

1. The combined resistance of two equal resistors connected in parallel is equal to
1. One half the resistance of one resistor.
2. Twice the resistance of one resistor.
3. Four times the resistance of one resistor.
4. One fourth the resistance of one resistor.

1. Superposition theorem can be applicable only to circuits having _________ elements.
1. Non- linear
2. Passive
3. Resistive
4. Linear bilateral

1. The Q- factor of a coil is given by
1. Its power factor cosF .
2. Ratio of max. energy stored & energy dissipated per cycle..
3. Reciprocal of its power factor.
4. Ratio R/Z.

1. The efficiency of a transformer is maximum when
1. It runs at half full load.
2. It runs at full load.
3. Its Cu loss equals iron loss.

1. The unit of inductance is
1. Ohm.
2. Mho.
4. Henry.

1. Thevenin’s equivalent circuit consists of _________.
1. Series combination of RTh, ETh and RL.
2. Series combination of RTh, ETh.
3. Parallel combination of RTh, ETh.
4. Parallel combination of RTh, ETh and RL.

1. An atom's atomic number is determined by the number of:
1. neutrons minus protons
2. protons
3. electrons
4. neutrons

1. In an R – L –C circuit, the phase of the current with respect to the circuit voltage will
be_________.
2. Same.
3. Lagging.
4. Depends upon the value of Land C.

1. The negative and positive charge symbols are assigned (in that order) to the:
1. proton and electron
2. electron and proton
3. atom and nucleus
4. electron and element

1. A voltmeter is used:
1. to measure current
2. in series with the circuit
3. in parallel with the circuit
4. to measure coulombs

1. Q factor of an inductive coil is given by
1. R/Z
2. 2πfr/R
3. 2πfL/R
4. lr/l

1. If the readings of the two wattmeters in the 2-wattmeter method of power measurement are 4.5
kW and 3.5 kW respectively and the latter reading has been obtained after reversing the
current coil of the wattmeter. What will be the total power in kW?
1. 1
2. 3.5
3. 4.5
4. 8

1. If the current in a circuit equals 0 A, it is likely that the
1. voltage is too high
2. resistance is too low
3. circuit has a short
4. circuit is open

1. What are the unit and symbol for current
1. Ampere, A
2. Coulomb, I
3. Ampere, Q
4. Ampere, I

1. A network that does not have either voltage or current sources is called
1. Active network.
2. Passive network.
3. Resistive network.
4. Dummy network.

1. The Power- factor at resonance in R-L-C circuit is
1. Zero.
2. Unity.
3. 0.5 lagging.

1. Resistance of a wire is r ohms. The wire is stretched to double its length, then its resistance
in ohms is
1. r/2
2. 4r
3. 2r
4. r/4

1. Which of the following will remain the same in all parts of a series circuit?
1. Voltage
2. Current
3. Power
4. Resistance

1. Which one of the following statements is not true?
1. Capacitance is a measure of a capacitor’s capability to store charge.
2. A capacitor offers high impedance to ac but very low impedance to dc.
3. A capacitor is also used as bypass capacitor.
4. Capacitors are used to couple alternating voltages from one circuit to another and at the same time to block dc voltage from reaching the next circuit.

1. In a Zener diode large reverse current is due to
1. collision.
2. presence of impurities.
3. rupture of bonds
4. lower resistance in reverse biased region.

1. JFET has main drawback of
1. having low input impedance.
2. having high output impedance.
3. being noisy.
4. small gain-bandwidth product

1. Which voltage source converts chemical energy to electrical energy?
1. Electrical generator
2. Battery
3. Solar cell
4. Electronic power supply

1. One coulomb passing a point in one second is one:
1. ampere
2. volt
3. ohm
4. charge

1. How many valence shell electrons are there in semiconductor atoms?
1. 6
2. 8
3. 4
4. 2

1. For thermionic emission
1. a material with high work function is preferable.
2. a material with low work function is preferable.
3. the work function of the material has no importance.
4. None of these is true.

1. Which unit of charge contains 6.25 × 1018 electrons?
1. An ampere
2. A coulomb
3. A volt
4. A joule

1. A switch is a device that:
1. short circuits complex circuits
2. holds a fuse
3. has double poles
4. opens or completes a current path

1. The CE configuration amplifier circuits are preferred over CB configuration amplifier circuits because they have
1. Lower amplification factor.
2. Larger amplification factor.
3. high input resistance and low output resistance.
4. none of these.

1. Which electronics material opposes the movement of free electrons?
1. Conductor
2. Insulator
3. Semiconductor
4. Element

1. Current is considered as the movement of:
1. electrons
2. protons
3. charge
4. nuclei

1. The colour band sequence of a resistor is grey, Blue, gold, and gold. The range in which its value must lie so as to satisfy the tolerance specified is between
1. 7.5Ω and 8.5Ω
2. 3.12KΩ and 5.22KΩ
3. 10.3KΩ and 12.31KΩ
4. 8.17Ω and 9.03Ω

1. In an N-type semiconductor, the concentration of minority carriers mainly depends upon
1. the doping technique.
2. the number of donor atoms.
3. the temperature of the
4. the quality of the intrinsic material,Ge or Si.

1. A basic electric circuit is made up of what components?
1. A load, a resistor, and a conductive path for current
2. A voltage source, a load, and a conductive path for current
3. A voltage source, a conductive path for current, and a battery
4. A conductive path for current, a battery, and a copper wire

1. A short circuit will have:
1. a small current flow
2. a large current flow
3. no current flow
4. some current flow

1. Which of the following statements is true?
1. Unlike charges repel and like charges attract.
2. Like charges repel and unlike charges attract.
3. Unlike charges attract and like charges attract.
4. Like charges repel and unlike charges repel.

1. When forward bias is applied to a junction diode, it
1. increases the potential barrier.
2. decreases the potential barrier.
3. reduces the majority-carrier current to zero.
4. reduces the minority-carrier current to zero.

1. A UJT contains
1. four pn junctions
2. three pn junctions
3. two pn junctions
4. one pn junction

1. Which of the following components are all active components?
1. A resistor and a capacitor.
2. A microphone, a LCD and a Thyratron.
3. An electric bulb, a transformer and a varactor diode.
4. An SCR, a vacuum diode and an LED.

1. Doping materials are called impurities because they
1. Decrease the number of charge carriers.
2. Change the chemical properties of semiconductors.
3. Make semiconductors less than 100 percent pure.
4. Alter the crystal structures of the pure semiconductors

1. Avalanche breakdown is primarily dependent on the phenomenon of
1. Collision
2. Doping
3. Ionisation
4. Recombination

1. The main reason why electrons can tunnel through a P-N junction is that
1. They have high energy.
2. Barrier potential is very low.
3. Depletion layer is extremely thin.
4. Impurity level is low.

1. If a change in base current does not change the collector current, the transistor amplifier is said
to be
1. Saturated.
2. Cut-off.
3. Critical.
4. Complemented.

1. The extremely high input impedance of a MOSFET is primarily due to the
1. Absence of its channel.
2. Negative gate-source voltage.
3. Depletion of current carriers.
4. Extremely small leakage current of its gate capacitor.

1. After firing an SCR, the gating pulse is removed. The current in the SCR will
1. Remains the same.
2. Immediately fall to zero.
3. Rise up.
4. Rise a little and then fall to zero.

1. A device whose characteristics are very close to that of an ideal voltage source is
1. a vaccum diode.
2. a DIAC.
3. a zener diode.
4. a FET.

1. The forbidden energy gap in semiconductors
1. lies just below the valance band
2. lies just above the conduction band
3. lies between the valence band and the conduction band
4. is the same as the valence band

1. The barrier potential for a Ge PN junction is
1. 0.6V.
2. 0.3V.
3. 0.1V.
4. 0.5V.

1. In a BJT, if the emitter junction is reverse-biased and the collector junction is reverse-biased, it
is said to operate in
1. in active region
2. in saturation region
3. in cut-off region
4. none of the above

1. The resistance between bases of a UJT is typically in the range of
1. 2 to 3 K Ω
2. 5 to 10 K Ω
3. 15 to 20 K Ω
4. 18 to 20 K Ω

1. With increasing temperature, the resistivity of an intrinsic semiconductor decreases. This is because, with the increase of temperature
1. The carrier concentration increases but the mobility of carriers decreases.
2. Both the carrier concentration and mobility of carriers decreases.
C. The carrier concentration decreases, but the mobility of carriers increases.
D. The carrier concentration remains the same but the mobility of carriers decreases.

1. The extremely high input impedance of a MOSFET is Primarily because of
1. Absence of its channel
2. Depletion of current carriers
3. Extremely small leakage current of its gate capacitor
4. Negative VGS

1. The “Superposition theorem” is essentially based on the concept of
A. duality
B. linearity
C. reciprocity
D. non-linearity

1. Cells are connected in parallel in order to
1. increase the voltage available.
2. reduce cost of wiring.
3. increase the current available.
4. reduce the time required to fully charge them after use

1. The power factor of a purely resistive circuit is
1. zero.
2. unity.
3. lagging.

1. The power taken by a 3-phase load is given by the expression
1. 3VL IL cos f .
2. 3 VL IL sin f .
3. 3 VL IL cos f .
4. 3 VL IL sin f .

1. Which of the following generating stations has the minimum running cost
1. hydro-electric station.
2. nuclear power station.
3. thermal power station.
4. diesel power plant.

1. Which of the following motors has a high starting torque?
1. ac series motor.
2. dc series motor.
3. induction motor.
4. synchronous motor.

1. The effect of increasing the length of the air gap in an induction motor will be to increase
1. power factor.
2. speed.
3. magnetising current.
4. air-gap flux.

1. The combined resistance of two equal resistors connected in parallel is equal to
1. One half the resistance of one resistor.
2. Twice the resistance of one resistor.
3. Four times the resistance of one resistor.
4. One fourth the resistance of one resistor.

1. Superposition theorem can be applicable only to circuits having _________ elements.
1. Non- linear
2. Passive
3. Resistive
4. Linear bilateral

1. The Q- factor of a coil is given by
1. Its power factor cosF .
2. Ratio of max. energy stored & energy dissipated per cycle..
3. Reciprocal of its power factor.
4. Ratio R/Z.

1. The efficiency of a transformer is maximum when
1. It runs at half full load.
2. It runs at full load.
3. Its Cu loss equals iron loss.

1. The unit of inductance is
1. Ohm.
2. Mho.
4. Henry.

1. Thevenin’s equivalent circuit consists of _________.
1. Series combination of RTh, ETh and RL.
2. Series combination of RTh, ETh.
3. Parallel combination of RTh, ETh.
4. Parallel combination of RTh, ETh and RL.

1. An atom's atomic number is determined by the number of:
1. neutrons minus protons
2. protons
3. electrons
4. neutrons

1. In an R – L –C circuit, the phase of the current with respect to the circuit voltage will
be_________.
2. Same.
3. Lagging.
4. Depends upon the value of Land C.

1. The negative and positive charge symbols are assigned (in that order) to the:
1. proton and electron
2. electron and proton
3. atom and nucleus
4. electron and element

1. A voltmeter is used:
1. to measure current
2. in series with the circuit
3. in parallel with the circuit
4. to measure coulombs

1. Q factor of an inductive coil is given by
1. R/Z
2. 2πfr/R
3. 2πfL/R
4. lr/l

1. If the readings of the two wattmeters in the 2-wattmeter method of power measurement are 4.5
kW and 3.5 kW respectively and the latter reading has been obtained after reversing the
current coil of the wattmeter. What will be the total power in kW?
1. 1
2. 3.5
3. 4.5
4. 8

1. If the current in a circuit equals 0 A, it is likely that the
1. voltage is too high
2. resistance is too low
3. circuit has a short
4. circuit is open

1. What are the unit and symbol for current
1. Ampere, A
2. Coulomb, I
3. Ampere, Q
4. Ampere, I

1. A network that does not have either voltage or current sources is called
1. Active network.
2. Passive network.
3. Resistive network.
4. Dummy network.

1. The Power- factor at resonance in R-L-C circuit is
1. Zero.
2. Unity.
3. 0.5 lagging.

1. Resistance of a wire is r ohms. The wire is stretched to double its length, then its resistance
in ohms is
1. r/2
2. 4r
3. 2r
4. r/4

1. Which of the following will remain the same in all parts of a series circuit?
1. Voltage
2. Current
3. Power
4. Resistance

1. Which one of the following statements is not true?
1. Capacitance is a measure of a capacitor’s capability to store charge.
2. A capacitor offers high impedance to ac but very low impedance to dc.
3. A capacitor is also used as bypass capacitor.
4. Capacitors are used to couple alternating voltages from one circuit to another and at the same time to block dc voltage from reaching the next circuit.

1. In a Zener diode large reverse current is due to
1. collision.
2. presence of impurities.
3. rupture of bonds
4. lower resistance in reverse biased region.

1. JFET has main drawback of
1. having low input impedance.
2. having high output impedance.
3. being noisy.
4. small gain-bandwidth product

1. Which voltage source converts chemical energy to electrical energy?
1. Electrical generator
2. Battery
3. Solar cell
4. Electronic power supply

1. One coulomb passing a point in one second is one:
1. ampere
2. volt
3. ohm
4. charge

1. How many valence shell electrons are there in semiconductor atoms?
1. 6
2. 8
3. 4
4. 2

1. For thermionic emission
1. a material with high work function is preferable.
2. a material with low work function is preferable.
3. the work function of the material has no importance.
4. None of these is true.

1. Which unit of charge contains 6.25 × 1018 electrons?
1. An ampere
2. A coulomb
3. A volt
4. A joule

1. A switch is a device that:
1. short circuits complex circuits
2. holds a fuse
3. has double poles
4. opens or completes a current path

1. The CE configuration amplifier circuits are preferred over CB configuration amplifier circuits because they have
1. Lower amplification factor.
2. Larger amplification factor.
3. high input resistance and low output resistance.
4. none of these.

1. Which electronics material opposes the movement of free electrons?
1. Conductor
2. Insulator
3. Semiconductor
4. Element

1. Current is considered as the movement of:
1. electrons
2. protons
3. charge
4. nuclei

1. The colour band sequence of a resistor is grey, Blue, gold, and gold. The range in which its value must lie so as to satisfy the tolerance specified is between
1. 7.5Ω and 8.5Ω
2. 3.12KΩ and 5.22KΩ
3. 10.3KΩ and 12.31KΩ
4. 8.17Ω and 9.03Ω

1. In an N-type semiconductor, the concentration of minority carriers mainly depends upon
1. the doping technique.
2. the number of donor atoms.
3. the temperature of the
4. the quality of the intrinsic material,Ge or Si.

1. A basic electric circuit is made up of what components?
1. A load, a resistor, and a conductive path for current
2. A voltage source, a load, and a conductive path for current
3. A voltage source, a conductive path for current, and a battery
4. A conductive path for current, a battery, and a copper wire

1. A short circuit will have:
1. a small current flow
2. a large current flow
3. no current flow
4. some current flow

1. Which of the following statements is true?
1. Unlike charges repel and like charges attract.
2. Like charges repel and unlike charges attract.
3. Unlike charges attract and like charges attract.
4. Like charges repel and unlike charges repel.

1. When forward bias is applied to a junction diode, it
1. increases the potential barrier.
2. decreases the potential barrier.
3. reduces the majority-carrier current to zero.
4. reduces the minority-carrier current to zero.

1. A UJT contains
1. four pn junctions
2. three pn junctions
3. two pn junctions
4. one pn junction

1. Which of the following components are all active components?
1. A resistor and a capacitor.
2. A microphone, a LCD and a Thyratron.
3. An electric bulb, a transformer and a varactor diode.
4. An SCR, a vacuum diode and an LED.

1. Doping materials are called impurities because they
1. Decrease the number of charge carriers.
2. Change the chemical properties of semiconductors.
3. Make semiconductors less than 100 percent pure.
4. Alter the crystal structures of the pure semiconductors

1. Avalanche breakdown is primarily dependent on the phenomenon of
1. Collision
2. Doping
3. Ionisation
4. Recombination

1. The main reason why electrons can tunnel through a P-N junction is that
1. They have high energy.
2. Barrier potential is very low.
3. Depletion layer is extremely thin.
4. Impurity level is low.

1. If a change in base current does not change the collector current, the transistor amplifier is said
to be
1. Saturated.
2. Cut-off.
3. Critical.
4. Complemented.

1. The extremely high input impedance of a MOSFET is primarily due to the
1. Absence of its channel.
2. Negative gate-source voltage.
3. Depletion of current carriers.
4. Extremely small leakage current of its gate capacitor.

1. After firing an SCR, the gating pulse is removed. The current in the SCR will
1. Remains the same.
2. Immediately fall to zero.
3. Rise up.
4. Rise a little and then fall to zero.

1. A device whose characteristics are very close to that of an ideal voltage source is
1. a vaccum diode.
2. a DIAC.
3. a zener diode.
4. a FET.

1. The forbidden energy gap in semiconductors
1. lies just below the valance band
2. lies just above the conduction band
3. lies between the valence band and the conduction band
4. is the same as the valence band

1. The barrier potential for a Ge PN junction is
1. 0.6V.
2. 0.3V.
3. 0.1V.
4. 0.5V.

1. In a BJT, if the emitter junction is reverse-biased and the collector junction is reverse-biased, it
is said to operate in
1. in active region
2. in saturation region
3. in cut-off region
4. none of the above

1. The resistance between bases of a UJT is typically in the range of
1. 2 to 3 K Ω
2. 5 to 10 K Ω
3. 15 to 20 K Ω
4. 18 to 20 K Ω

1. With increasing temperature, the resistivity of an intrinsic semiconductor decreases. This is because, with the increase of temperature
1. The carrier concentration increases but the mobility of carriers decreases.
2. Both the carrier concentration and mobility of carriers decreases.
C. The carrier concentration decreases, but the mobility of carriers increases.
D. The carrier concentration remains the same but the mobility of carriers decreases.