Electronics Solved Quiz on circuit theory

Electronics Solved Quiz on circuit theory
Circuit Theory Solved Question
1. Ohm’s law applicable for
(a) linear circuits only
(b) non linear circuits only
(c) both linear and non linear circuits
(d) none of these
Ans: a
2. Unit of current is
(a) Ampere
(b) Volt
(c) Watt
(d) Volt-ampere
Ans: a
3. What is the equivalent resistance when 10 Ohms and 20 Ohms resistors are connected
in series
(a) 35 Ohms
(b) 25 Ohms
(c) 30Ohms
(d) none of these
Ans: c
4. Form factor is defined as the ratio of
(a) Average value to Maximum value
(b) Maximum value to Average value
(c) Peak value to R.M.S Value
(d) R.M.S Value to Average value
Ans: d
5. R.M.S Value of full wave rectified sinusoidal voltage is
(a) V_M/3
(b) V_M/2
(c) V_M/Ö2
(d) none of these
Ans: c
6. Power factor for resistive load is
(a) Zero
(b) Unity
(c) Infinity
(d) 0.2
Ans: b
7. voltage is a ------quantity
(a) Scalar
(b) Vector
(c) Scalar and Vector
(d) none of these
Ans: b
8. In D.C , Capacitor acts as
(a) Short circuit
(b) Open circuit
(c) either (a)or (b)
(d) none of these
Ans: b
9 In 3 phase star circuit, phase voltage is
(a) V_Ph =Ö3 V_L
(b) V_Ph = V_L /Ö3
(c) V_Ph = V_L
(d) V_Ph =3 V_L
Ans: b
10. In 3 phase delta circuit, line current is
(a) I_L =I _Ph
(b) I_L =2 I _Ph
(c) I_L =3 I _Ph
(d) I_L =Ö3 I _Ph
Ans:d
11. What is the equivalent resistance when 20Ohms and 20Ohms resistors are
connected in parallel
(a) 45 Ohms
(b) 10Ohms
(c) 54 Ohms
(d) 30Ohms
Ans: b
12. Voltage-Current relationship in resistor element is
(a) In phase
(b) Out of phase
(c) No Relation
(d) constant
Ans:a
13. For high voltage applications which type of 3 phase circuit to be Preferred
(a) Star
(b) Delta
(c) Star or Delta
(d) Neither Star nor Delta
Ans: b
14. What is the unit of Reactive Power
(a) KVA
(b) KW
(c) HP
(d) KVAR
Ans:d
15. R.M.S Value of Half wave rectified sinusoidal voltage is
(a) V_M/3
(b) V_M/2
(c) V_M/Ö2
(d) none of these
Ans: b
16. Current is defined as
(a) Charge/time
(b) Time/charge
(c) power/time
(d) None of these
Ans:a
17. Active elements are
(a) Voltage sources only
(b) Current sources only
(c) Resistors only
(d) Both Voltage and Current sources
Ans: d
18. In Bilateral Network the current flows in
(a) Unidirectional
(b) Bidirectional
(c) Rotational
(d) None of these
Ans: b
19. D.C has
(a) Constant magnitude
(b) Variable magnitude
(c) Fixed Polarities
(d) Constant magnitude and Fixed Polarities
Ans: d
20. In Capacitive circuit, Current flows in the capacitor
(a) i=C (dv/dt)
(b) i=V(dc/dt)
(c) i=C(di/dt)
(d) i=Ct
Ans: a
21. Unit of voltage is
(a) Ampere
(b) Volt
(c) Watt
(d) Volt-ampere
Ans: b
22. Peak factor is defined as the ratio of
(a) Average value to Maximum value
(b) Maximum value to Average value
(c) Peak value to R.M.S Value
(d) R.M.S Value to Average value
Ans: c
23. Average value is
(a) area/period
(b) period/area
(c) length/area
(d) none of these
Ans: a
24. Unit of power is
(a) Ampere
(b) Volt
(c) Watt
(d) joules
Ans:c
25. Unit of apparent power is
(a) Ampere
(b) Volt
(c) Watt
(d) Volt-ampere
Ans:d
26. Unit of energy is
(a) KWH
(b) Volt
(c) Watt
(d) Volt-ampere
Ans:a
27. A.C has
(a) Constant magnitude
(b) Variable magnitude
(c) Fixed Polarities
(d) Constant magnitude and Fixed Polarities
Ans: b
28. Passive elements are
(a) Voltage sources only
(b) Current sources only
(c) Resistors ,inductors and capacitors
(d) Both Voltage and Current sources
Ans: c
29. In D.C , inductor acts as
(a) Short circuit
(b) Open circuit
(c) both (a)&(b)
(d) none of these
Ans: a
30. In Unilateral Network the current flows in
(a) Unidirectional
(b) Bidirectional
(c) Rotational
(d) None of these
Ans: a
31. Workdone is
(a) F.d
(b) E/F
(c) IR
(d) None of these
Ans: a
32. Unit of Resistance is
(a) Ampere
(b) Volt
(c) Watt
(d) ohms
Ans: d
33. Unit of inductance is
(a) Ampere
(b) Volt
(c) Watt
(d) henry
Ans: d
34. Unit of capacitance is
(a) Ampere
(b) farad
(c) Watt
(d) henry
Ans: b
35. For high current applications which type of 3 phase circuit is Preferred
(a) Star
(b) Delta
(c) Star or Delta
(d) Neither Star nor Delta
Ans: a
36. For low voltage applications which type of 3 phase circuit to be Preferred
(a) Star
(b) Delta
(c) Star or Delta
(d) Neither Star nor Delta
Ans: a
37. Unit of charge is
(a) Ampere
(b) coulomb
(c) Watt
(d) henry
Ans: b
38. EMF is
(a) Election motion force
(b) Electrical motion force
(c) Electro motive force
(d) None of these
Ans: c
39. MMF is
(a) Magnetic motive force
(b) Magnetic motion force
(c) Magneto motive force
(d) None of these
Ans: c
40. Voltage-Current relationship in inductor element is
(a) In phase
(b) 90 (lead)
(c) 90 (lag)
(d) constant
Ans: c
41. Voltage-Current relationship in capacitor element is
(a) In phase
(b) 90 (lead)
(c) 90 (lag)
(d) constant
Ans: b
42. When two inductors are connected in series, equivalent inductance is
(a) L1+L2
(b) 1/(L1+L2)
(c) L1.L2
(d) None of these
Ans: a
43. When two capacitors are connected in series, equivalent capacitance is
(a) C1+C2
(b) 1/(C1+C2)
(c) L1.L2
(d) (1/c1)+(1/c2)
Ans: d
44. R.M.S Value of full wave rectified sinusoidal voltage is
(a) V_M/3
(b) V_M/2
(c) V_M/Ö2
(d) none of these
Ans:c
45. Form factor of full wave rectified sinusoidal voltage is
(a) 1.21
(b) 1.11
(c) 4.44
(d) none of these
Ans: b
46. Power factor for pure inductor
(a) 0(lead)
(b) 0
(c) 0(lag)
(d) none of these
Ans: c
47. Power factor for pure capacitor
(a) 0(lead)
(b) 0
(c) 0(lag)
(d) none of these
Ans: a
48. Frequency is defined as
(a) No of cycles/sec
(b) time/cycles
(c) 1/cycles
(d) None of these
Ans: a
49. In Series resistive circuit, voltage across each resistor is
(a) divided
(b) constant
(c) no change
(d) None of these
Ans: a
50. In Series resistive circuit current through each resistor is
(a) divided
(b) same
(c) 0
(d) None of these
Ans:b
51. When two inductors are connected in parallel, equivalent inductance is
(a) L1+L2
(b) (1/L1)+(1/L2)
(c) L1.L2
(d) None of these
Ans: b
52. When two capacitors are connected in parallel, equivalent capacitance is
(a) L1+L2
(b) (1/L1)+(1/L2)
(c) C1+C2
(d) None of these
Ans:c
53.A sinusoidal Wave form is
a)sine wave form
b) triangle wave form
c) both(a)&(b)
d)none of these
Ans:a
54. In 3 phase delta circuit, phase voltage is
(a) V_Ph =Ö3 V_L
(b) V_Ph = V_L /Ö3
(c) V_Ph = V_L
(d) V_Ph =3 V_L
Ans: c
55. In 3 phase star, line current is
(a) I_L =I _Ph
(b) I_L =2 I _Ph
(c) I_L =3 I _Ph
(d) I_L =Ö3 I _Ph
Ans:a

Free Online Practice test on Electronics

Free Online Practice test  on Electronics
Free Electronics Online Practice Test
Free Online Electronic Engineering Practice and Preparation test
1. UPS is
a. Uninterrupted power supply
b. Unlimited power supply
c. United power supply
d. None of these
Ans. a
2. UPS is a device which maintains continuous supply of ______ to the system connected
a. Electric power
b. Magnetic power
c. EMF
d. Resistance
Ans. a
3. _________ Supplies power when utility is not available.
a. AC mains
b. DC mains
c. UPS
d. SMPS
Ans. C
4. Types of UPS are
a. Switch on and offline UPS
b. Off line and on line UPS
c. Standard and normal ups
d. Power UPS
Ans. b
5. Diode is a combination of
a. Two electrons
b. Two electrodes
c. Two elements
d. Two capacitors
Ans. b
6. How many types of crystal diode rectifiers are there?
a. 2
b. 3
c. 4
d. 5
Ans. a
7. In half wave rectification, the rectifier conducts current only in _____of input ac supply.
a. Positive half cycle
b. Negative half cycle
c. Neutral
d. Both a and b
Ans. a
8. RMS value of current in half wave rectifier is
a. Im/?2
b. Im/2
c.2Im/Em
d. Em/2
Ans b
9. The transformer isolates the rectifier circuit form power line and thus reduces
a. Electric shock
b. Current loss
c. Resistance loss
d. Transformer
Ans. a
10. The pulsations in the output are further smoothening with the help of _________circuit.
a. Transformer
b. Diode
c. Filter
d. Transistor
Ans. c
11. The ratio of dc power output to the applied input of rectifier is known as
a. Power
b. Rectification efficiency
c. Utility factor
d. Working efficiency
Ans. b
12. In half wave rectification, a maximum of _______of ac power is rectifier.
a. 40%
b. 40.6%
c. 40.9%
d. 80.1%
Ans. b
13. The rectifier which contains 2 diodes is called
a. Full wave rectifier
b. Half wave rectifier
c. Centre – tap rectifier Full wave rectifier
d. Bridge full wave rectifier
Ans. c
14. Bridge full wave rectifier consists of ………… number of diodes.
a. 2
b. 3
c. 4
d. 6
Ans. c
15. The efficiency of full wave rectifier is
a. 40%
b. 40.6%
c. 81.2%
d. 80% Ans. c
16. A power supply which maintains the voltage constant irrespective of ac main fluctuations or load variations is known as
a. DC power supply
b. DC regulated power supply
c. Steady power supply
d. None of these
Ans. B
17. A dc regulate supply uses a for power regulation.
a. Transformer
b. Transistor
c. Capacitor
d. Zener diode
Ans. d
18. The process in which an ac voltage is converted into a unidirectional dc voltage is known as
a. Rectification
b. Conversion
c. Transformation
d. Regulation
Ans. a
19. When forward biased, junction diode offers
a. High resistance
b. Low resistance
c. No resistance
d. None of these
Ans. b
20. In the rectifier circuits the ac supply form mains is given through ______ for transformation.
a. Amplifier
b. Transformer
c. Diode
d. Load resistor
Ans. b
21. The ac supply to be rectified in half wave rectifier is applied in series with
a. Diode and load resistance
b. Load resistance and transformer
c. Diode and regulated power supply
d. Two diode
Ans. a
22. An AC rectifier which rectifies both the positive and negative ac half cycles of input wave are called
a. Half wave rectifier
b. Full wave rectifier
c. Transformation rectifier
d. None of these
Ans. b
23. In full – wave rectifier the direction of current in load resistor is ____________ for both half cycles of ac.
a. Opposite
b. Same
c. Different
d. None of these
Ans. b
24. The expression for peak inverse voltage, in case of centre – tap full wave rectifier is
a. 2Vm
b. Vm
c. Vm/2
d. 3Vm
Ans. a
25. In on line UPS ________ batteries are used earlier
a. semiconductor
b. ionic
c. Lead – acid
d. Ordinary
Ans. b
26. Large UPS units typically work in conjunction with
a. Motor
b. Batteries
c. Generator
d. Transformer
Ans. c
27. SMPS are classified into _______ types depending up its input / output.
a. 3
b. 2
c. 4
d. 6
Ans. c
28. SMPS with ac input and dc output is used as
a. Current converter
b. Frequency changer
c. Rectifier
d. cycle converter
Ans. c
29. SMPS with dc input and ac output is used as
a. Current converter
b. Frequency changer
c. Rectifier
d. Inverter
Ans. d
30. Linear power supplies use a transformer operating at the mains frequency of ______ Hz.
a. 50
b. 60
c. 50 or 60
d. none of these
Ans. C
31. SMPS use transformer operating at the frequency of ___________
a. 50 Hz to 1 kHz
b. 50 kHz to 1 kHz
c. 5 kHz to 1MHz
d. 50 kHz to 10MHz
Ans. b
32. The applied ac power to a half wave rectifier is 100W the ac output power obtained is 40W.the rectification efficiency is
a. 30%
b. 40%
c. 50%
d. 60%
Ans. b