Computer Science - Electronic Principles MCQs Part 1

1. In an intrinsic semiconductor, the number of free electrons

A.
Equals the number of holes

B.
Is less than the number of holes

C.
Is greater than the number of holes

D.
Impossible to say

E.
None of the above

 Answer Option A

2. A device that converts mechanical into electrical energy is?

A.
solar cell

B.
thermocouple

C.
chemical cell

D.
generator

E.
None of the above

 Answer Option D

3. Which one of the following kinds of materials has the lowest permeability?

A.
A diamagnetic material

B.
A paramagnetic material

C.
A feiTomagnetic material

D.
All of the above

E.
None of the above

 Answer Option A

4. The total impedance of a parallel RLC circuit:

A.
always increases as the applied frequency increases

B.
is equal to the sum of the values of resistance, inductive reactance and capacitive reactance

C.
always decreases as the applied frequency increases

D.
is maximum at the resonant frequency

E.
None of the above

 Answer Option D

5. The rise time of a pulse waveform is the time required for the voltage to rise:

A.
from zero to its rms value

B.
from zero to its peak value

C.
from 10% of the peak value to 70.7% of the peak value

D.
from 10% of the peak value to 90% of the peak value

E.
None of the above

 Answer Option D

6. For a pure capacitor:

A. ac current and voltage are exactly in phase

B. ac current leads the voltage by 90 degree

C. ac current is converted to dc voltage

D. ac current lags the voltage by 90 degree

E. None of the above

 Answer Option B

7. The component that forms the electrical connection between the rotating coil of wire in a motor and the external source of electrical energy is called the:

A. rotor

B. armature

C. battery

D. commutator

E. None of the above

 Answer Option D

8. In a pure inductor:

A. ac current leads the voltage by 90 degree

B. ac current and voltage are exactly in phase

C. ac current lags the voltage by 90 degree

D. ac current is converted to dc voltage

E. None of the above

 Answer Option C

9. Waveforms are graphs that show:

A. frequency on the vertical axis and amplitude on the horizontal axis

B. amplitude on the vertical axis and frequency on the horizontal axis

C. amplitude on the vertical axis and the passage of time on the horizontal axis

D. the passage of time on the vertical axis and amplitude on the horizontal axis

E. None of the above

 Answer Option C

10. When the collector current increases, what does the current gain do?

A. decreases

B. stays the same

C. increases

D. any of the above

E. None of the above

 Answer Option C

11. How many types of flow are there in a semiconductor?

A. 0

B. 1

C. 2

D. 3

E. None of the above

 Answer Option B

12. Which one of the following devices is most often used for measuring opposition to current flow in a circuit?

A. Ammeter

B. Voltmeter

C. Ohmmeter

D. Wattmeter

E. None of the above

 Answer Option C

13. What form of energy is used to maintain an imbalance of charges between the terminals of a battery?

A. Electronical energy

B. Mechanical energy

C. Chemical energy

D. Solar energy

E. None of the above

 Answer Option C

14. Which one of the following statements best applies to a parallel RLC circuit?

A. The voltage waveform for each component always has the same amplitude and phase as the applied voltage

B. The sum of the current is always less than the applied current

C. The current waveform for each component always has the same amplitude and phase as the applied current

D. All of the above

E. None of the above

 Answer Option A

15. The equivalent of 1 micro A is:

A. 10000A

B. 1000 A

C. one-millionth of an ampere

D. one million amperes

E. None of the above

 Answer Option C

16. Which one of the following statements best describes magnetic hysteresis?

A. Hysteresis is the amount of magnetic flux that is not confined to the core material of an electromagnet

B. Hysteresis is most apparent when a steady amount of current is lowing through the coil of an electromagnet

C. Hysteresis is most apparent when the current through the coil of an electromagnet changes frequently

D. Hysteresis is most apparent when the core material is saturated

E. None of the above

 Answer Option C

17. Which one of the following phrases best describes residual magnetism?

A. Magnetism that remains in the core of an electromagnet after the current through the coil is turned off

B. The force of attraction between the poles of a permanent and temporary magnetic field

C. The amount of magnetic flux that is not confined to the core material of an electromagnet

D. The circular magnetic field that surrounds a conductor carrying a current

E. None of the above

 Answer Option A

18. A transformer has a primary voltage of 120 V rms and a secondary voltage of 25 V rms. If the secondary current is 1A rms, what is the primary current?

A. 7.8 mA

B. 208 mA

C. 200 mA

D. 300 mA

E. None of the above

 Answer Option B

19. Household light bulbs have a given power rating, and they operate at 120 V. Which one of the following equations most directly provides the current rating of these light bulbs?

A. P = I2R

B. P = IE

C. P = E2/R

D. I = P/E

E. None of the above

 Answer Option D

20. Which one of the following phrases most accurately describes a purely inductive circuit?

A. Resistances provide the only opposition to current flow

B. Inductive reactance provides the only opposition to current flow

C. Combinations of resistance and inductive reactance provide any opposition to current flow

D. The ac voltage lags the current by 90 degree

E. None of the above

 Answer Option B

21. The knee voltage of a diode is approximately equal to the

A. Applied voltage

B. Barrier potential

C. Breakdown voltage

D. Forward voltage

E. None of the above

 Answer Option B

22. A zener regulator has an input voltage from 15 to 20 V and a load current from 5 to 20 mA. If the zener voltage is 6.8 V, what value should the series resistor have?

A. 310 Ohm

B. 400 Ohm

C. 410 Ohm

D. 550 Ohm

E. None of the above

 Answer Option C

23. The rms value of a sine waveform is:

A. the number of cycles completed in one second

B. the time required to complete one full cycle

C. equal to 0.707 times the peak amplitude

D. equal to 1.41 times the peak amplitude

E. None of the above

 Answer Option C

24. Which one of the following is a direct statement of Ohm's law?

A. The voltage drop across a resistance is proportional to the value of resistance and the amount of current flowing through it

B. The total resistance of a parallel circuit is less than the value of the smallest resistance

C. The algebraic sum of voltages in a loop is equal to zero

D. The algebraic sum of currents entering and leaving a point is equal to zero

E. None of the above

 Answer Option A

25. A high-pass filter:

A. passes lower-frequency signals and reduces higher-frequency signals

B. passes higher-frequency signals and reduces lower-frequency signals

C. has no effect on ac signals

D. increases the level of all frequencies by a significant amount

E. None of the above

 Answer Option B

26. Which one of the following statements is true for the voltages in a series RC circuit?

A. The total voltage is equal to the sum of the voltages across the resistance and capacitance

B. The voltage always has the same amplitude and phase for every part of the circuit

C. The total voltage is less than the sum of the voltages across the resistance and capacitance

D. The total voltage is greater than the sum of the voltages across the resistance and capacitance

E. None of the above

 Answer Option C

27. A battery is a device composed of one or more:

A. chemical cells

B. voltage generators

C. solar cells

D. piezoeletric cells

E. None of the above

 Answer Option A

28. Doubling the operating voltage of a purely capacitive circuit:

A. has no effect on the capacitive reactance

B. doubles the amount of capacitive reactance

C. multiplies the capacitive reactance by 7

D. cuts the capacitive reactance in half

E. None of the above

 Answer Option A

29. How much current flows through a 0.02-H choke that is operating from a 12-V ac, 100-Hz source?

A. 0.02 A

B. 0.955 A

C. 10 A

D. 2.02 A

E. None of the above

 Answer Option B

30. The transistor has a collector current of 10 mA and a base current of 40 mA. What is the current gain of the transistor?

A. 250 μA

B. 350 μA

C. 0.25 μA

D. 300 μA

E. None of the above

 Answer Option A

31. What is the phase shift between total current and voltage in the circuit of a 100 ohm resistor connected in parallel with a capacitor that has a reactance of 100 ohm

A. 180 degree

B. 30 degree

C. 45 degree

D. 75 degree

E. None of the above

 Answer Option C

32. Molecule is

A. The smallest particle of a substance that retains the properties of that substance

B. A atom that has a shortage of electrons in its outer orbit

C. A atom that has an excessive number of electrons in its outer orbit

D. A atom that flows whenever there is an imbalance of electrical charges between two points

E. None of the above

 Answer Option A

33. What form of energy is used for creating static electricity?

A. Solar energy

B. Mechanical energy

C. Chemical energy

D. Light energy

E. None of the above

 Answer Option D

34. Suppose the zener diode has a breakdown voltage of 10 V and zener resistance of 8.5 W, what is the additional voltage when the current is 20 mA?

A. 0.17 V

B. 10.17 V

C. 20 V

D. 18.8 V

E. None of the above

 Answer Option A

35. A transistor has a current gain of 125 and a base current of 30 µA. What is the collector current?

A. 3.75 mA

B. 3.2 mA

C. 0.05 mA

D. 13 mA

E. None of the above

 Answer Option A

36. A dielectric material is:

A. a good conductor

B. a good insulator

C. a poor conductor of electrostatic fields

D. a good conductor of magnetic fields

E. None of the above

 Answer Option B

37. A certain electromagnet has 1000 turns of wire. How much current must flow through the coil in order to generate an mmf of 100 ampere-turns?

A. 0.1 A

B. 1000 A

C. 10 A

D. 100 A

E. None of the above

 Answer Option B

38. If a load resistance is 1 kW, a stiff current source has a resistance of

A. At least 10 Ohm

B. Less than 10 Ohm

C. More than 100 k Ohm

D. Less than 100 k Ohm

E. None of the above

 Answer Option C

39. A flashlight battery has internal resistance of 1W. For what values of load resistance does the flashlight battery appear stiff?

A. 60 Ohm

B. 50 Ohm

C. 100 Ohm or more

D. 10 Ohm

E. None of the above

 Answer Option C

40. The number of free electrons and holes in intrinsic semiconductor increases when the temperature

A. Decreases

B. Increases

C. Stays the same

D. 0oC

E. None of the above

 Answer Option B

41. Which one of the following statements is true for current flowing in a parallel circuit?

A. The amount of current flow through each branch of a parallel circuit can be different, depending on the resistance of each branch part and the amount of voltage applied to it

B. The same current always flows through every part of a parallel circuit

C. The total current in a parallel circuit is equal to the total voltage multiplied by the total resistance

D. The total current in a parallel circuit is always less than the smallest amount of current

E. None of the above

 Answer Option A

42. Holes are the minority carriers in which type of semiconductor?

A. Extrinsic

B. Intrinsic

C. n-type

D. p-type

E. None of the above

 Answer Option C

43. Doubling the number of turns of wire in an inductor:

A. reduces the value of inductance by one-half

B. multiplies the value of inductance by two

C. multiplies the value of inductance by four

D. reduces the value of inductance by one-fourth

E. None of the above

 Answer Option C

44. A farad is defined as the amount of capacitance necessary for:

A. dissipating 1 W of power

B. causing an ac phase shift greater than 90 degree

C. storing 1 V for 1 second

D. changing the voltage on the plates at the rate of 1 V per second when 1 A of current is flowing

E. None of the above

 Answer Option D

45. What is the capacitive reactance of a 0.1 micro F capacitor that is operating at 1000 Hz?

A. less than 1 Ohm

B. 1590 Ohm

C. 312 Ohm

D. 690 Ohm

E. None of the above

 Answer Option B

46. A certain power transformer has a turns ratio of 5. What voltage can you expect at the secondary winding when you apply 120 V to the primary winding?

A. 4.73

B. 0.4 V

C. 24 V

D. 600 V

E. None of the above

 Answer Option C

47. Which one of the following statements is true for the currents in a parallel RC circuit?

A. The total current is equal to the sum of the currents for the resistance and capacitance

B. The current always has the same amplitude and phase for every part of the circuit

C. The total current is less than the sum of the currents for the resistance and capacitance

D. The total current. is greater than the sum of the currents for the resistance and capacitance

E. None of the above

 Answer Option A

48. Which one of the following statements is true for current flowing in a series circuit?

A. The amount of current flow through each part of a series circuit can be different, depending on the resistance of each part and the amount of voltage applied to it

B. The total current in a series circuit is equal to the sum of the currents flowing through the individual components in the circuit

C. The same current flows through every part of a series circuit

D. The total current in a series circuit is equal to the total voltage multiplied by the total resistance

E. None of the above

 Answer Option C

49. The total inductance of a series inductor circuit is:

A. equal to the sum of the individual inductance values

B. equal to the sum of the individual inductive-reactance values

C. less than the value of the smallest inductor

D. equal to the source voltage divided by total current

E. None of the above

 Answer Option A

50. When the graph of current versus voltage is a straight line, the device is referred to as

A. Active

B. Linear

C. Nonlinear

D. Bipolar

E. None of the above

 Answer Option B