### Computer Science - Electronic Principles MCQs Part 2

1. Which one of the following statements most accurately applies to the frequency of a waveform?

A.
The actual frequency of a sine waveform is 1.41 times the working frequency
B.
Unless specified otherwise, the frequency of a waveform is assumed to be 60 Hz
C.
The higher the amplitude of a waveform, the higher its frequency
D.
The longer the period of a waveform, the lower its frequency
E.
None of the above

2. The merging of a free electron and a hole is called

A.
Covalent bonding
B.
C.
Recombination
D.
Thermal energy
E.
None of the above

3. One henry of inductance is defined as:

A.
the amount of counter emf required to reduce a current to 1 A
B.
the amount of inductance required for generating 1 V of counter emf when the current changes at the rate of 1 A per second
C.
the amount of inductance required to change the frequency of a current by 1 Hz
D.
the number of turns of wire in an inductor multiplied by the amount of current flowing through it
E.
None of the above

4. The basic unit of measurement for current is the:

A.
volt
B.
watt
C.
ampere
D.
ohm
E.
None of the above

5. Which one of. the following phrases most accurately describes the nature of a pulsating dc voltage?

A.
The voltage remains at one polarity and at a steady level
B.
The voltage remains at one polarity but changes value periodically
C.
The voltage causes current to flow in two directions at the same time
D.
The voltage reverses polarity periodically
E.
None of the above

6. What is a negative ion?

A. An atom that contains more electrons than neutrons
B. An atom that contains more protons than neutrons
C. An atom that contains more electrons than protons
D. An atom that contains more protons than electrons
E. None of the above

7. In a transistor operates at the middle of the load line, an increase in the base resistance will move the Q point

A. down
B. up
C. nowhere
E. None of the above

8. Voltage is

A. The flow of charged particles through a material
B. The smallest electrically charged particle
C. Trie force that causes electrons to flow
D. The number of free electrons in an atom
E. None of the above

9. What is the turns ratio for the transformer specified in the above question?

A. 10.738
B. 0.707
C. 1.5
D. 0.575
E. None of the above

10. The total impedance of a series RLC circuit:

A. is minimum at the resonant frequency
B. always increases as the applied frequency increases
C. always decreases as the applied frequency increases
D. is maximum at the resonant frequency
E. None of the above

11. The direction of electron current flow is:

A. from right to left
B. from positive to negative
C. from negative to positive
D. from neutral to positive
E. None of the above

12. A device that converts mechanical pressure to electrical energy is called a:

A. piezoelectric device
B. solar cell
C. photodiode
E. None of the above

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

A. The voltage always has the same amplitude and phase for every part of the circuit
B. The total voltage is equal to the sum of the voltages across the resistance and capacitance
C. The total voltage leads the total current by less than 90 degree
D. The total voltage is less than the sum of the voltages across the resistance and capacitance
E. None of the above

14. The Thevenin resistance is equal in value to the

C. Internal resistance of a Morton circuit
E. None of the above

15. Most AC power is obtained from:

A. generators
B. batteries
C. oscillators
D. lightning
E. None of the above

16. The value of a capacitor can be made larger by:

A. increasing the area of the plates
B. decreasing the area of the plates
C. increasing the frequency of the applied voltage
D. increasing the voltage applied to the plates
E. None of the above

17. The value of a capacitor can be made larger by:

A. moving the plates further apart
B. moving the plates closer together
C. increasing the voltage applied to the plates
D. decreasing the voltage applied to the plates
E. None of the above

18. The primary impedance of a transformer is 60 ohm and the secondary impedance is 120 ohm. What is the impedance ratio?

A. 0.25
B. 180
C. 0.5
D. 4
E. None of the above

19. Suppose a voltage source has an ideal voltage of 12V and an internal resistance of 0.5W. For what values of load resistance will the voltage source appear stiff?

A. 5 Ohm
B. 50 Ohm or more
C. 100 Ohm
D. 6 Ohm
E. None of the above

20. Electron current is flowing through a conductor in a direction you might describe as straight into this page. What is the direction of the resulting magnetic field?

A. Clockwise
B. Counterclockwise
E. None of the above

21. Which one of the following principles best describes the basic operation of an electromagnet?

A. Current is induced in a conductor that is moving through a magnetic field
B. Like magnetic poles repel, while unlike poles attract
C. Current flowing through a conductor generates a magnetic field
D. Like magnetic poles attract, while unlike poles repel
E. None of the above

22. The transistor has a collector current of 2 mA. If the current gain is 135, what is the base current?

A. 14.8 ÂµA
B. 10.3 ÂµA
C. 7.8 ÂµA
D. 7.75 ÂµA
E. None of the above

23. Current and voltage are said to be in phase when:

A. their waveforms are both ac or both dc
B. they have the same amplitude and frequency
C. their waveforms cross through zero and reach positive and negative peaks at the same time
D. All of the above
E. None of the above

24. Silicon atoms combine into an orderly pattern called a

A. Crystal
B. Covalent bond
C. Semiconductor
D. Valence orbit
E. None of the above

25. The rotating coil of wire in an electric motor is called the:

A. armature
B. brush
C. commutator
D. loop
E. None of the above

26. The north pole of a magnet is the one:

A. that has its molecules arranged in a random pattern
B. that would be attracted to the earth's north magnetic pole
C. that would be repelled by the south pole of another magnet
D. that would be attracted to the earth's south magnetic pole
E. None of the above

27. A resistor has a rated value of 100 ohm and a tolerance of 10%. What is its minimum and maximum allowable resistance value?

A. 90 Ohm - 101 ohm
B. 90 Ohm - 110 ohm
C. 98 Ohm - 100.1 ohm
D. 99 Ohm - 102 ohm
E. None of the above

28. When a parallel RLC circuit is operating at its resonant frequency:

A. capacitive reactance is greater than the inductive reactance
B. inductive reactance is greater than the capacitive reactance
C. inductive reactance is equal to the capacitive reactance
D. the difference between inductive and capacitive reactance is equal to the resistance
E. None of the above

29. For normal operation of the transistor, the collector diode has to be

A. Forward-biased
B. Reverse-biased
C. Nonconducting
D. Operating in the breakdown region
E. None of the above

30. In a step-down transformer, which is larger?

A. Primary voltage
B. Secondary voltage
C. Neither
D. Impossible to say
E. None of the above

31. What is the barrier potential of a silicon diode at room temperature?

A. 0.7V
B. 0.3V
C. 1 V
D. 2 m V per degree Celsius
E. None of the above

32. The Norton current is sometimes called the

C. Thevenin current
D. Thevenin voltage
E. None of the above

33. At room temperature a conductor has low many holes?

A. Same number as free electrons
B. many
C. Only those produced by thermal energy
D. less than the free electrons
E. None of the above

34. A current source has an internal resistance of 100 kW. What is the largest load resistance if the current source must appear stiff?

A. 2 k Ohm
B. 10 k Ohm
C. 20 k Ohm
D. 1 k Ohm
E. None of the above

35. When the Q point moves along the load line, the voltage increases when the current

A. Decreases
B. Stays the same
C. Increases
D. Can be any of above
E. None of the above

36. What is the smallest number of polarities required for current flow?

A. One - a negative terminal
B. Two - a negative terminal and a positive terminal
C. Three - negative, positive and neutral terminals
D. Four - two negative and two positive
E. None of the above

37. A diode is in series with 220W. If the voltage across the resister is 4V, what is the current through the diode?

A. 55 A
B. 55.86 A
C. 18.2 mA
D. 16.3 mA
E. None of the above

38. Two diodes are in series. The first diode has a voltage of 0.75 V and the second has a voltage of 0.8 V. If the current through the first diode is 500 mA, what is the current through the second diode

A. 11 mA
B. 12 mA
C. 10 mA
D. 14 mA
E. None of the above

39. The graph of current gain versus collector current indicates that the current gain

A. varies enormously
B. is contant
C. varies slightly
D. equals the collector current divided by the base current
E. None of the above

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

A. The total current is equal to the sum of the currents through the resistance and inductance
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 through the resistance and inductance
D. The total current leads the total voltage by less than 90
E. None of the above

41. What is the impedance of a circuit composed of a 100 ohm resistor connected in parallel with an inductor that has a reactance of 200 W?

A. 77.7 ohm
B. 89.3 ohm
C. 88.8 ohm
D. 224 ohm
E. None of the above

42. The nucleus of the copper atom contains how many protons?

A. 1
B. 4
C. 18
D. 29
E. None of the above

43. Which one of the following statements is true for voltage in a series circuit?

A. The total voltage is equal to the sum of the individual voltages in a series circuit
B. The total voltage in a series circuit is equal to the average value of the individual voltages
C. The total voltage of a series circuit is equal to the total current divided by the total resistance
D. The total voltage in a series circuit is always less than the value of the smallest voltage
E. None of the above

44. A basic capacitor is composed of:

A. two conductors separated by a dielectric
B. two dielectrics separated by a conductor
C. two coils separated by a dielectric
D. two coils separated by a conductor
E. None of the above

45. Which one of the following devices is most often used for measuring electrical potential difference?

A. Voltmeter
B. Ohmmeter
C. Ammeter
D. Wattmeter
E. None of the above

46. Which one of the following equations most directly determines the power dissipation of a resistance when you know the voltage drop and amount of resistance?

A. P = I2R
B. P = IE
C. P = E2/R
D. I = P/E
E. None of the above

47. The equivalent of 1 megohms is:

A. 1 k ohm
B. 100,000 ohm
C. one-millionth of an ohm
D. one million ohms
E. None of the above

48. Which one of the following equations most directly determines the amount of current flowing through a resistor when you know the value of the resistor and the voltage drop across it?

A. E = PR
B. E = I2R
C. I = E/R
D. I = ER
E. None of the above

49. Suppose a current source has an Ideal current of 10 mA and an internal resistance of 20 MW. For what values of load resistance will the current source appear stiff?

A. 20 k Ohm or more
B. 200 k Ohm or less
C. 200 k Ohm or more
D. 20 km or less
E. None of the above

50. If the current gain is 200 and the collector current is 100 mA, the base current is

A. 2 mA
B. 0.5 mA
C. 2 A
D. 200 A
E. None of the above