MOD.3 (PART 1) - ELECTRICAL FUNDAMENTALS

1) The mark-to-space ratio of the waveform shown is: A to B / B to C. A to D / D to E. D to E / D to C.

2) In what equipment is a photon radiated when an electron leaves a hole?. Photo-cell. LED. Photo diode.

3) The unit which consists of two or more different types of atoms is known as a: particle of an element. molecule of a compound. molecule of an element.

4) A neutron has: no electrical charge but will add weight to the nucleus. the same charge as an Electron but half the mass. the opposite charge to an Electron but half the weight of a proton.

5) The smallest particle that a substance can be split and show the same properties as the whole is known as: an Element. a Molecule. an Atom.

6) What charge does the nucleus of an atom possess?. Positive. Neutral. Negative.

7) What is the maximum number of electrons in shell N of an atom?. 18. 32. 16.

8) An oxygen molecule is made up of: two oxygen atoms sharing neutrons. two oxygen atoms sharing protons. two oxygen atoms sharing electrons.

9) If electrons are added to an atom it becomes: a neutral ion. a positive ion. a negative ion.

10) A element whose atoms have fewer than 4 electrons in their valency shell are: semiconductors. good insulators. good conductors.

11) The charge of a proton is: positive. negative. neutral.

12) What effect do the electrons of one atom have upon the electrons of another atom?. They have no effect on each other. They repel each other. They attract each other.

13) What is a molecule?. The smallest part of an atom. The smallest part of a compound. The smallest part of an electron.

14) An atom is: The smallest part of an element that retains its charateristics. The smallest part of a compound that can exist independently. The smallest particle of matter.

15) A neutron is a particle which is: is contained in the nucleus of all atoms. orbits the nucleus of the atom. is contained within the nucleus of most atoms.

16) The mass of an atom is contained mainly in the: proton. nucleus. electron.

17) When the atom loses or gains an electron it is called: a molecule. a current. an ion.

18) A good electrical insulator is a material which: contains a large number of positive ions. has its electrons tightly bound to their parent atoms. has more protons than electrons.

19) An electric current is: an ordered flow of electrons. a surplus of free electron. an excitement of electron in a metal.

20) An atom contains: hydrogen. molecules. electrons.

21) Germanium and silicon have how many electrons in their outer shell?. 6. 4. 2.

22) If a free electron is given to another atom, that atom is a: valency atom. negative ion. positive ion.

23) The atomic number of an atom is determined by the number of: protons. electrons. neutrons.

24) The valency electron is: the electron in outer shell of atom. the electron in inner shell of atom. a positive electron.

25) An atom with deficiency in electrons has: low resistance. high resistance. high impedance.

26) An atom with less than 4 electrons in its outer shell has: low electrical resistance. no electrical resistance. high electrical resistance.

27) Element such as phosphorus with 5 electrons in their outer shell, when combined with pure silicon, is a: isotopic. acceptor. donor.

28) An hydrogen atom consist of a: proton, neutron and an electron. proton and an electron only. neutron and a proton only.

29) For a atom to become a negative ion it must: gain at least one electron. have undergone ionisation by the sun. lose at least one electron.

30) What is the maximum number of electrons in shell M of an atom?. 18. 6. 16.

31) A neutral atom with an atomic no. of 3 has how many electrons?. 1. 3. dependant on type of atom.

32) The nucleus of an atom is: neutral. positive charge. negative charge.

33) Electron orbits are called: waves. shells. valences.

34) A neutron atom gains electrons: It gains a positive charge. It gains a negative charge. It remains neutral.

35) An oxygen atom has: protons and electrons. neutrons and protons. protons, neutrons and electrons.

36) A semi-conductor will have: two electrons in the outer shell. four electrons in the outer shell. eight electrons in the outer shell.

37) Ion current is found in: contuctors and semi-conductors. liquid and gasses. semi-conductors.

38) Electricity conducts through: vacuum. solids and liquids only. solids only.

39) An example of a good electrical insulator is: aluminium. glass. mercury.

40) Static charges remaining in an aircraft are dissipated by: earthing the aircraft as soon as possible. the use of a conducting type nose wheel. bonding the aircraft to a refuel tanker.

41) An element could be considered to be a conductor if it has: a small number of electrons in its outer orbit. a large number of electrons in its outer orbit. a large number of electrons.

42) A charged body is said to have: a surplus or deficiency of electrons. a deficiency of neutrons. a surplus of protons.

43) The risk of a fire due to static electricity is overcome: by connecting all metal components by bonding. by fitting static wicks and isolating the battery from inflammable gas sources. by fitting static wicks and isolating all metal components.

44) The purpose of bonding is to: ensure all components have been securely fitted. stop different potentials developing with fire risks. give generated static an easy return path to the generator.

45) The varius parts of an aircraft airframe are maintained at the same potential by: the supply bus-bars. bonding. static discharge wicks.

46) The resistance of the current return path through the aircraft is always considered negligible, provided the: structure is adequately bonded. voltage drop across the circuit is checked. generator is properly grounded.

47) If an insulated conductor is placed near to a negatively charged rod, the nearest end of the conductor becomes: no change will occur. negatively charged. positively charged.

48) The electromagnetic force between two charged bodies is: inversely proportional to the distance between them. inversely proportional to the square of the distance between them. proportional to the distance between them.

49) If a negatively charged conductor is placed next to an insulated rod: the becomes negatively charged. the rod has no charge. the rod becomes positively charged.

50) If a photon radiating into an electronic device causes the production of an electron/hole pair, the device is known as a: light emiting diode. laser diode. photodiode.

51) Faraday's Law States that: the magnitude of the EMF is indirectly proportional to the rate of change of flux. the magnitude of the EMF is directly proportional to the magnitude flux. the magnitude of the EMF is directly proportional to the rate of change of flux.

52) Which of the following is 1 Amp?. 1000 mA. 1000 ka. 1000 1/4A.

53) The term that describes the combined resistive forces in an AC circuit is: resistance. total resistance. impedance.

54) Ohm's law states that: m.f. = current divided by resistance. current = e.m.f. divided by resistance. resistance = current divided by e.m.f.

55) E.M.F. is an electric circuit corresponds to what in a magnetic circuit: MMF. reluctance. flux.

56) In conventional current flow, what is Fleming's right hand rule used for?. generators. motors. inductors.

57) The SI unit of work is: kilogram metres-force. joules per metre. joules per second (Watts).

58) A coulomb is: one ampere * second. one second per ampere. one ampere per second.

59) A volt can be considered to be a: unit of electrical power. quantity of electrical energy. unit of electrical pressure.

60) What is 3.25 volts in millivolts?. 3,250 millivolts. 325,000 millivolts. 3.25 millivolts.

61) Electromotive force is measured in: watts. ohms. volts.

62) The basis for transformer operation in the use of alternating current is mutual: inductance. capacitance. reactance.

63) When two coils are linked by a common flux, a voltage can be induced in one by a changing current in the other. This process is known as: self induction. the magnetic effect. mutual induction.

64) When an electrical supply becomes "open-circuit"?. the fuse or circuit breaker should isolate the circuit due to the increased current drawn. the loss of continuity will prevent its component from functioning. the component will operate normally but will not switch off.

65) The S.I. unit of magnetic flux density is the: Henry. Weber. Tesla.

66) A 1uF capacitor is equivalent to: 1,000,000 Farads. 000,001 Farads. 001 Farads.

67) The opposition offered by a coil to the flow of alternating current is called (disregarding resistance). inductive reactance. impedance. reluctance.

68) A shunt is used with: an ammeter. a voltmeter. an ohmmeter.

69) If a load in series has a current passing through it, the magnetic field can be worked out by using: the corkscrew rule. left hand rule. right hand rule.

70) The unit for power is: Joules per second. N/m. Volts/Amps.

71) In conventional flow, the left hand rule applies to: generators. batteries. motors.

72) When a conductor is cut by magnetic lines of force an EMF is induced. This is: Lenz's Law. Faraday's Law. Kirchhoff's Law.

73) The Watt can be expressed as: Seconds per Joule. Joules * seconds. Joules per second.

74) To determine the direction of the magnetic field around a conductor you would use: Fleming's right hand rule. Fleming's left hand rule. The corkscrew rule.

75) Switching on or off the current in one coil produces an emf in another coil adjacent to it. The two coils are said to have: self inductance. auto inductance. mutual inductance.

76) Self induced emf in a coil supplied with a current varying at a uniform rate can be found by: -L d / dt. -N dI / dt. -L dI / dt.

77) The property of a material to accept lines of flux is called: retentivity. reluctance. permeability.

78) Magnetomotive force can be found by: I * N. Blv. N/I.

79) When a conductor is cut by magnetic lines of force an EMF is induced. This is: Kirkchoff`s Law. Faraday`s Law. Lenz`s Law.

80) The direction of induced conventional current in a wire rotating in a magnetic field can be determined by: cork screw rule. Fleming`s right hand rule. Fleming`s left hand rule.

81) How would you find the direction of the electron flow in an armature located in a magnetic field?. Flemings left hand rule. Flemings right hand rule. Maxwells corkscrew rule.

82) What is the SI unit of conductance?. Ohm. Siemen. Ohm-metre.

83) What is the SI unit of resistivity?. Ohms. Ohm metre. Ohms/metre.

84) What is the formula for conductance? (R=Resistance). R + 1. 1/R. 1-R.

85) In electrical circuit, Direct Current power is represented by the: Ampere. Watt. Joule.

86) In S.I. units, work is denoted by: Newton-meter which is Joules. Joules/sec which is Watts. Kilogram-force-meter/sec which is Metric Horsepower.

87) The unit of energy is the: Joule. Watt. Coulomb.

88) Potential difference is another term for: voltage. charge. energy.

89) XL is the symbol of: inductive reactance. capacitive reactance. impedance.

90) Using Ohm`s law: current is directly proportional to the resistance. current is directly proportional to the EMF. resistance is directly proportional to EMF.

91) One volt is induced into a circuit with a current varying at 1 amp per second. The circuit has: 1 ampere turn. 1 Tesla. 1 Henry.

92) The property of a conductor of electricity that limits or restricts the flow of electric current is: limiter. resistance. fuse.

93) Kirchhoff`s law is applicable to: parallel networks. series networks. closed loop networks.

94) The SI unit of work is the: Watt. Newton Meter. Joule.

95) The EMF of a generator can be calculated from which law?. Faraday`s law. Kirchhoff`s law. Lenz`s law.

96) Thermocouple harnesses are made from the same materials as the thermocouple so that?. mini junctions are not formed. the resistance is not increased beyond limits. they will not corrode.

97) A piezoelectric device generates electricity through: friction. light. pressure.

98) A photozoidal cell produces electricity when subjected to?. light. pressure. heat.

99) A thermocouple indicator is basically a type of: millivoltmeter. milliammeter. milliohmeter.

100) A light/heat sensitive cell is a: transistor. diode. transducer.

101) A component that produces an output voltage due to incident light is called a: liquid crystal. solar cell. light emitting diode.

102) The flux density of a magnetic field is 1.5T. The length of the conductor in the field is 2 m and the speed of the conductor is 10 m/s. The EMF induced is: 3 V. 5 V. 30 V.

103) A conductor is placed in a magnetised coil. What will happen?. Nothing will happen unless the conductor is moved. The conductor will move. A force will be created.

104) The maximum output voltage from a basic single loop generator is when the loop is: rotating anti-clockwise relative to the direction of the magnetic flux. cutting maximum lines of magnetic flux. at 45° to the magnetic flux.

105) A 20 cell battery with each cell having an internal resistance of 0.1 ohms is charged with 2 leads having a total resistance of 0.1 ohms. The battery is charged with a current of 5 amps. What is the charging voltage?. 0.5 volts. 10.5 volts. 0.05 volts.

106) Two 10V, 20 Ah batteries are connected in parallel and connected across a 10 ohm load. How long could they supply normal current before the voltage begins to decay?. 40 hours. 20 hours. 4 hours.

107) A battery rated at 40 Ah will supply 200 mA for?. 200 hours. 20 hours. 5 hours.

108) A zinc-carbon battery life depends upon: the amount of zinc. the purity of the carbon rod. the amount of the electrolyte paste.

109) When checking the Specific Gravity (S.G.) of the electrolyte in a lead acid battery, you should?. check any cell because they will all be the same. check only the no. 1 cell because it is the master cell. check all cells because they may be different.

110) The PD at the terminals of an open circuit battery with a small internal resistance will be?. more than the EMF. less than the EMF. the same as the EMF.

111) An accumulation of hydrogen on the plates of a battery is known as: polarization. ionization. hydration.

112) What part of a battery is covered in hydrogen during polarization?. Anode. Both the anode and the cathode. Cathode.

113) Which of the following is most likely to cause thermal runaway in a nickel-cadmium battery?. A high internal resistance condition. High current charging of the battery to more than 100 percent of its capacity. Excessive current draw from the battery.

114) The method of ascertaining the voltage of a standard aircraft lead-acid battery is by checking: the voltage with rated load switched ON. the voltage on open circuit. the voltage off load.

115) Two batteries 12V and 40 Ah each, are in series. What is the total capacity?. 12V 80 Ah. 24V 40 Ah. 24V 80Ah.

116) If a battery has got low internal resistance, then the: no load voltage will be the same as on load voltage. on load voltage will be greater than no load voltage. no load voltage will be greater than on load voltage.

117) Conventional current flow inside a battery is from: either anode to cathode or cathode to anode, depending on the active elements. cathode to anode. anode to cathode.

118) In a voltaic cell, what is the build-up on the cathode called?. Hydration. Polarization. Sulphation.

119) Two 12V 40 amp hour batteries connected in parallel will produce: 24V 80 ah. 12V 80 ah. 24V 40 ah.

120) A 24-volt source is required to furnish 48 watts to a parallel circuit consisting of four resistors of equal value. What is the voltage drop across each resistor?. 12 volts. 24 volts. 3 volts.

121) The method of ascertaining the voltage of a standard aircraft lead-acid battery is by checking: the voltage on open circuit. the voltage off load. the voltage with rated load switched ON.

122) Two similar 12v batteries connected in parallel will produce: 24v e.m.f. with the same capacity as each battery. 12V e.m.f. with twice the capacity of each battery. 24V e.m.f. with twice the capacity of each battery.

123) The voltage of a secondary cell is: determined by the active materials on the plates. determined by the number of plates. determined by the area of the plates.

124) What is the ampere-hour rating of a storage battery that is designed to deliver 45 amperes for 2.5 hours?. 90 ampere-hour. 112.5 ampere-hour. 45 ampere-hour.

125) If a nicad battery is not to be used immediately it should be stored: dry. fully charged. fully dissipated.