ABE TUTORIALS

VOLUME 10- AREA 3

1. Materials that oppose the flow of electric current.

a. Rubber

b. Conductor

c. Semi-conductor

d. Insulators

Explanation: Insulators are materials that prevent or significantly oppose the flow of electrons. While rubber is an insulator, "insulators" is the correct general classification.

2. H is the unit of inductance and it is equivalent to 1 volt-sec per ________.

a. farad

b. ohm

c. Henry

d. Amp

Explanation: One Henry (H) is defined as the inductance that produces a self-induced EMF of 1 volt when the current changes at the rate of 1 Ampere per second (V * s / A).

3. Electrical resistance of conductors is commonly proportional to the:

a. resistivity

b. length

c. area

d. temperature

Explanation: Resistance (R) is directly proportional to length (L) and resistivity (rho), and inversely proportional to cross-sectional area (A).

4. This type of wire consists of wires twisted to form a metallic string.

a. cable

b. solid wire

c. stranded wire

d. co-axial

Explanation: Stranded wire is composed of several small-gauge wires bundled or wrapped together to form a larger conductor, providing more flexibility than solid wire.

5. The property of an electric circuit that opposes a change in current.

a. capacitance

b. impedance

c. inductance

d. none of the above

Explanation: Inductance is the electrical property that resists any change in the magnitude or direction of current.

6. Unity power factor loads are electrical loads that contain:

a. pure capacitance

b. pure resistance

c. pure impedance

d. none of the above

Explanation: In a purely resistive load, the voltage and current are in phase, resulting in a power factor of 1.0 (unity).

7. It is a device used for transferring electrical energy from one circuit to another without a change in frequency.

a. diode

b. transformer

c. motor

d. none of them

Explanation: A transformer uses electromagnetic induction to transfer power between circuits while maintaining the same frequency.

8. This refers to the circuit that extends from the panel board to a group of outlets or to a single utilization equipment.

a. distribution line

b. branch circuit

c. small appliance outlet

d. bus

Explanation: A branch circuit is the final portion of the wiring system that delivers electricity to the equipment or outlets.

9. It is the device used to measure the energy consumed over a period of time.

a. watt-hour meter

b. watt meter

c. galvanometer

d. power factor meter

Explanation: A watt-hour meter measures electrical energy (Power x Time), which is the basis for utility billing.

10. This refers to all circuit conductors from the service equipment up to the final utilization outlets.

a. service wire

b. feeder

c. branch circuit

d. distribution wire

Explanation: Feeders are the conductors between the service equipment/main disconnect and the final branch-circuit overcurrent device.

11. It is the short length of wire used to make a connection between a terminal or around a break in a circuit.

a. junction

b. connector

c. jumper

d. junction box

Explanation: A jumper is a short conductor used to bypass or connect points in a circuit.

12. It is the centroidal point of the electrical system.

a. pole

b. indoor

c. outdoor

d. load center

Explanation: The load center is the point where the electrical loads of a facility are concentrated or centrally distributed.

13. What is that factor with which the VA must be multiplied in order to obtain the actual power?

a. power factor

b. voltage regulation

c. resistive factor

d. inductance

Explanation: Real Power (Watts) = Apparent Power (VA) * Power Factor (cos theta).

14. When measuring a DC voltage and the meter pointer deflects to the left you should:

a. increase the range of the meter

b. change the meter

c. interchange the test probe

d. stop the measuring

Explanation: A leftward deflection on an analog DC meter indicates reversed polarity. Interchanging the probes fixes this.

15. The Philippine Electrical Code specifies that all wall switches be installed on the ________ of the door.

a. left side

b. hinge side

c. latch side

d. front side

Explanation: Switches should be installed on the latch side of the door so they are easily accessible when entering a room.

16. An ideal gas is compressed isothermally. The enthalpy change is:

a. always negative

b. sometimes negative

c. zero

d. sometimes positive

e. always positive

Explanation: For an ideal gas, enthalpy is a function of temperature only. If the process is isothermal (delta T=0), delta H is zero.

17. Select the material with the highest thermal conductivity.

a. air

b. copper

c. glass

d. steel

e. water

Explanation: Copper is an excellent conductor of both heat and electricity, significantly outperforming the other materials listed.

18. In an “ideal” situation, what is the COP of a refrigeration cycle that is operating between -40°C and 30°C?

a. 0.5

b. 0.0

c. 3.0

d. 5.0

e. 7.0

Explanation: COP = TL / (TH - TL). TL is 233K and TH is 303K. Calculation: 233 / (303 - 233) = 233 / 70, which is approximately 3.3. Check your source for the specific temperature range used.

19. Two just saturated air-vapor mixtures are thoroughly mixed. The final stage of the mixture is:

a. still saturated

b. unsaturated

c. completely condensed out

d. partly condensed out

e. no way to tell

Explanation: Because the saturation curve on a psychrometric chart is concave, mixing two saturated air masses at different temperatures results in a supersaturated mixture, causing partial condensation (fog).

20. Generally, palay can be stored safely up to 2 to 3 months at moisture content of:

a. 28%

b. 24%

c. 18%

d. 14%

e. 10%

Explanation: 14% moisture content is the standard for short-to-medium term storage of paddy rice in the tropics.

21. The recommended temperature for long term storage of fresh food products is:

a. ambient temperature

b. just above freezing

c. at freezing point

d. just below freezing

e. at low freezing temperature

Explanation: For "long-term" storage (frozen foods), temperatures should be maintained well below freezing, typically -18°C.

22. The expression used to indicate the amount of bran removed in the milling process is called:

a. bran recovery

b. degree of milling

c. head rice recovery

d. milling percentage

e. milling recovery

Explanation: Degree of milling describes how much of the bran layers and germ have been removed from the brown rice.

23. The amount of foreign materials or impurities from a sample of paddy which is usually expressed as percentage is called:

a. chaff

b. dockage

c. immature grains

d. purity

e. scalper

Explanation: Dockage refers to all material other than the grain itself, such as weed seeds, stalks, and dust.

24. The average yield per hectare (tons/ha) of palay in the Philippines is about:

a. 0.5

b. 1

c. 3

d. 4-5

e. 15

Explanation: Average yields in the Philippines typically range between 4.0 and 4.5 tons/ha depending on the season and irrigation.

25. A type of dryer wherein the flow of air is transverse to the direction of flow of the product being dried is called:

a. batch

b. circulating

c. concurrent

d. counter-flow

e. cross-flow

Explanation: In a cross-flow dryer, air moves perpendicular (transverse) to the grain column.

26. Equalization of moisture or temperature throughout the product, bringing to a desired moisture content or temperature for processing is called:

a. drying

b. tempering

c. curing

d. aeration

e. dehydration

Explanation: Tempering allows moisture from the core of the grain to move to the surface between drying passes, preventing stress cracks.

27. Kinetic energy is the energy of the body due to its:

a. elevation

b. temperature

c. motion

d. pressure

Explanation: Kinetic energy (1/2 mv^2) is directly related to the velocity of an object.

28. Power is work done:

a. 33,000 ft-lb

b. per unit time

c. 2450 kg

d. work times distance

Explanation: Power is the rate of doing work (P = W / t).

29. Area under T-s diagram is defined as:

a. work

b. heat

c. change in internal energy

d. none of the above

Explanation: For a reversible process, the area under the Temperature-entropy curve represents the heat transferred.

30. Thermodynamics cycle used in thermal power plants:

a. Ericsson

b. Brayton

c. Rankine

d. Carnot

Explanation: The Rankine cycle is the ideal model for steam power plant systems.

31. The state of a pure substance is defined completely if we define:

a. pressure and temperature

b. two independent intensive properties

c. two intensive properties

d. any two properties

Explanation: According to the state postulate, the state of a simple compressible system is completely specified by two independent, intensive properties.

32. Torque is a force that tends to produce:

a. tension

b. compression

c. rotation

d. bending

Explanation: Torque (moment of force) is a measure of the force that can cause an object to rotate about an axis.

33. A rigid container is heated by the sun. There is no shaft work associated with the container. From the first law of thermodynamics, you determine the heat added to be:

a. equal to the work

b. equal to the change in internal energy

c. equal to zero

d. equal to unity

Explanation: For a rigid container (V=constant, so W=0), the First Law (Q - W = delta U) simplifies to Q = delta U.

34. If a centrifugal pump tends to vibrate, it might be caused by:

a. misalignment

b. worn bearings

c. clogged or damaged impeller

d. Any of the above

Explanation: Vibration in centrifugal pumps is a common symptom of mechanical imbalance, wear, or hydraulic issues.

35. A pyrometer measures:

a. temperature

b. pressure

c. volume

d. mass

Explanation: A pyrometer is a type of remote-sensing thermometer used to measure high temperatures, often surface temperature of distant objects.

36. The steam power cycle is modeled by the ideal cycle known as the:

a. Otto Cycle

b. Brayton Cycle

c. Rankine Cycle

d. Diesel Cycle

Explanation: Rankine is the model for steam, Otto for gasoline engines, Diesel for diesel engines, and Brayton for gas turbines.

37. What is the power in kW produced by a 100 HP engine?

a. 74.6

b. 80.5

c. 150

d. 125

Explanation: One horsepower (HP) is equivalent to 0.746 kilowatts (kW). 100 x 0.746 = 74.6 kW.

38. Refers to the temperature at which molecular motion ceases, according to the kinetic theory of heat.

a. critical point

b. triple point

c. absolute zero

d. absolute temperature

Explanation: Absolute zero (0 K or -273.15C) is the theoretical temperature at which all thermal motion of molecules stops.

39. As heat is removed from a substance it gets colder. When no more heat can be removed and the temperature cannot be lowered any further, we have reached:

a. perfect zero

b. absolute zero

c. double zero

d. cold zero

Explanation: This is the definition of absolute zero on the thermodynamic temperature scale.

40. The lower horizontal line of the refrigeration cycle plotted on the pressure enthalpy diagram represents:

a. compression of refrigerant vapor

b. evaporation of liquid refrigerant

c. condensation of refrigerant vapor

d. metering of liquid refrigerant

Explanation: In a P-h diagram, the bottom horizontal line represents constant-pressure evaporation in the evaporator.

41. In which part of vapor compression system is there a change in both pressure and temperature?

a. Evaporator

b. condenser

c. compressor

d. dryer

Explanation: The compressor increases the pressure of the vapor, which also significantly raises its temperature.

42. What refrigerant is most commonly used for air conditioning of passenger aircraft?

a. ammonia

b. R-11

c. CO2

d. air

Explanation: Aircraft use an "Air Cycle Machine" which uses environmental air as the refrigerant due to safety and weight considerations.

43. A continuous-flow type dryer in which the drying bin is a columnar type with louvers causing mixing to occur as the grain flows through the system.

a. Mixing type

b. Non-mixing type

c. Recirculating type

d. None of the above

Explanation: Mixing type dryers use baffles or louvers to ensure the grain is agitated for uniform drying.

44. Pressure build up in the plenum chamber to maintain uniform distribution of air flow through the grain mass.

a. Velocity pressure

b. Static pressure

c. Dynamic pressure

d. Two of the above

Explanation: Static pressure is the force required to push the air through the resistance of the grain bed.

45. It indicates the uniformity of grind in the resultant product.

a. Uniformity sex

b. Particle size

c. Fineness modulus

d. All of the above

Explanation: Fineness modulus is a numerical value that describes the particle size distribution of ground feed.

46. The percentage speed difference between rubber huller rollers.

a. 15%

b. 20%

c. 25%

d. None of the above

Explanation: Rubber rollers in rice hullers rotate at different speeds (typically a 25% difference) to create the shearing force needed to remove the husk.

47. When a bucket elevator is to be fed at the downside section instead of the upside section of the elevator boot, its power requirement will:

a. Decrease

b. Increase

c. The same

d. None of the above

Explanation: Feeding on the "down" side (against the direction of travel) requires the buckets to dig through the material, significantly increasing resistance and power needs.

48. A rice mill huller which produces high milling recovery.

a. Steel huller

b. Rubber huller

c. Stone disk

d. None of the above

Explanation: Rubber roll hullers are gentler on the grain than steel or stone, resulting in fewer broken kernels and higher recovery.

49. An example of moisture determination using a primary method.

a. Resistance type meter

b. Capacitance type meter

c. Oven

d. All of the above

Explanation: The oven-drying method is a primary (direct) method. Electrical meters are secondary (indirect) methods.

50. In grain drying theory, drying will occur if:

a. The vapor pressure of grain is higher than the vapor pressure of air

b. The vapor pressure of grain is lower than the vapor pressure of air

c. The vapor pressure of grain is equal with the vapor pressure of air

d. None of the above

Explanation: Moisture moves from high vapor pressure to low vapor pressure. For drying, the grain must "push" moisture into the air.

51. It is the indicator of the quality of food which determines whether or not it is acceptable to the consumers.

a. Taste

b. Flavor

c. Palatability

d. None of the above

Explanation: Palatability refers to the overall appraisal of food based on its physical and chemical properties, making it agreeable to the palate.

52. A process used for many food products by giving aeration treatment to improve the color, flavor, aroma retention, or reduce the volume of the product.

a. Degassing

b. Blending

c. Exhausting

d. All of the above

Explanation: Degassing (or deaeration) removes entrapped gases to prevent oxidation and improve the sensory qualities of food.

53. Pre-drying temperature requirement for mushroom.

a. 80-90°F

b. 120-125°F

c. 250-300°F

d. None of the above

Explanation: Mushrooms are sensitive to heat; 120-125°F is a common range to prevent enzymatic browning and maintain texture during the initial drying stage.

54. A pre-treatment procedure to keep the color and quality of vegetables before drying.

a. trimming

b. Blanching

c. Salting

d. None of the above

Explanation: Blanching inactivates enzymes that cause spoilage and off-colors in vegetables.

55. Any tag, brand mark, pictorial, or other descriptive matter, written, printed, marked, embossed or impressed on, or attached to a container of food.

a. Nutrition facts

b. Label

c. Trademark

d. None of the above

Explanation: A label is the general term for all descriptive material on a product's packaging.

56. Beam is a basic structural element that supports a load perpendicular to:

a. the x-axis

b. its longitudinal axis

c. the y-axis

d. its cross section

Explanation: By definition, a beam is designed to carry transverse loads (perpendicular to its length).

57. A wood beam is checked for its strength and resistance against:

a. shear, bending, deflection compression

b. shear, bending, buckling compression

c. shear, moment, deflection compression

d. shear, bending, deflection, bearing

Explanation: Design checks for wood beams include horizontal shear, bending stress, deflection limits, and bearing at supports.

58. A straight carbon steel which contains 0.20 to 0.60% carbon is called:

a. low carbon steel

b. high carbon steel

c. medium carbon steel

d. alloy steel

e. nota

Explanation: Medium carbon steel ranges from 0.20% to 0.60%, whereas low carbon is below 0.20% and high carbon is above 0.60%.

59. Deals with the relation between the externally applied loads and their internal effects on bodies assumed not ideally rigid.

a. mechanics

b. static

c. strength of materials

d. kinetics

Explanation: Strength of materials (mechanics of deformable bodies) focuses on the internal stresses and strains within objects.

60. Deals with the relation of forces acting on bodies in equilibrium.

a. mechanics

b. statics

c. Strength of materials

d. kinematics

Explanation: Statics is the branch of mechanics that analyzes loads on physical systems in static equilibrium.

61. The deformation when the load is released after reaching the elastic limit of the material.

a. zero

b. temporary

c. permanent

d. none

Explanation: Once the elastic limit is exceeded, the material undergoes plastic deformation and will not return to its original shape.

62. The slope of the stress-strain diagram under proportional limit:

a. ductility

b. elasticity

c. strain

d. stress

Explanation: The slope is the Modulus of Elasticity (E), representing the stiffness or elasticity of the material.

63. Beam having excess supports that requires additional equations to obtain the reactions.

a. statics

b. statically indeterminate

c. statically determinate

d. kinetics

Explanation: If equations of statics (total Force = 0, total Moment = 0) are insufficient to solve for unknowns, the structure is statically indeterminate.

64. The ratio of ultimate stress and allowable stress.

a. tolerance

b. allowance

c. factor of safety

d. ultimate ratio

Explanation: Factor of Safety (FS = ultimate stress / allowable stress) provides a margin for design uncertainty.

65. States that “within the range of elastic behavior, the elongation is proportional to the tensile force”:

a. Newton’s law

b. Hooke’s law

c. strain

d. Poisson’s ratio

Explanation: Hooke's Law states that stress is directly proportional to strain within the elastic limit (stress = E * strain).

66. The deformation due to twisting of fiber.

a. angular

b. axial

c. flexural

d. elongation

Explanation: Torsion or twisting results in an angular displacement (angle of twist).

67. The equivalent of 746 Watts in HP.

a. 556.52

b. 655.25

c. 565.52

d. 1

Explanation: 1 HP is equal to 746 Watts (or 0.746 kW).

68. Merely the graphical visualization of shear and moment.

a. equation

b. diagram

c. support

d. graph

Explanation: Shear and Moment diagrams are standard engineering tools used to visualize internal forces along a beam.

69. Beam supported by hinge and a roller reaction, with either or both ends extending beyond the supports.

a. simple

b. cantilever

c. overhanging

d. rod

Explanation: An overhanging beam has supports that are not at the extreme ends.

70. Beam supported only at one end.

a. simple

b. cantilever

c. overhanging

d. rod

Explanation: A cantilever beam is fixed at one end and free at the other.

71. It is the process of removing heat from a substance or space at a lower temperature.

a. Sublimation

b. Heat of fusion

c. Refrigeration

d. All of the above

Explanation: Refrigeration is the process of cooling a space or substance to a temperature below that of its surroundings.

72. The quantity of heat in the substance is described in terms of:

a. BTU

b. Calories

c. Pascal

d. All of the above

Explanation: Heat (energy) can be measured in BTUs, Calories, or Joules. Pascal is a unit of pressure.

73. Ten BTU is equivalent to:

a. 2520 calories

b. 2250 calories

c. 2045 calories

d. None of the above

Explanation: 1 BTU is approximately 252 calories, so 10 BTU is approximately 2520 calories.

74. It is the quantity of heat required to raise the temperature of a substance one degree scale.

a. Sensible heat

b. Specific heat

c. Latent heat

d. None of the above

Explanation: Specific heat is the heat capacity per unit mass.

75. It is the cooling coil of a refrigeration system.

a. Condenser

b. Evaporator

c. Compressor

d. None of the above

Explanation: The evaporator is where the refrigerant absorbs heat from the space being cooled.

76. The introduction of fresh ambient air to an air-conditioned or refrigerated space.

a. Cooling

b. Air changes

c. Air filtration

d. None of the above

Explanation: "Air changes per hour" (ACH) is a measure of ventilation and how many times the total volume of air is replaced.

77. Lowest temperature that is safe for storage of banana is:

a. Below 14°C

b. below 5°C

c. Below 0°C

d. All of the above

Explanation: Bananas are susceptible to chilling injury if stored below 13-14°C.

78. It is the process of exposing freshly harvested product and carefully prepared food to subzero temperatures and holding them at -32°C during storage period to maintain the quality of the products.

a. Cold storage

b. Quick freezing

c. Sharp freezing

d. All of the above

Explanation: Cold storage is the broader term for holding products at low temperatures to slow biological decay.

79. Most favorable cold storage temperature for eggs.

a. 29-30°C

b. 29-30°F

c. 28°F

d. None of the above

Explanation: Eggs are stored just above their freezing point (approx. 28°F) to maximize shelf life without cracking the shell.

80. A freezer that operates at an air temperature of -30°F and below and a velocity of 500 to 1000 fpm.

a. Sharp freezer

b. Air blast freezer

c. Contact plate freezer

d. All of the above

Explanation: Air blast freezers use high-velocity cold air to achieve rapid freezing.

81. A 3 hp engine is to be replaced with an electric motor. Recommend for the size of the motor for the drive.

a. 1 hp

b. 2 hp

c. 5 hp

d. None of the above

Explanation: Electric motors have better torque and efficiency; usually, a 2 HP motor can replace a 3 HP gasoline engine.

82. In order to minimize darkening of carcass of poultry meat, it is recommended that before cold storage poultry meat should be:

a. Slowly be frozen and undergo scalding process

b. Frozen rapidly

c. Undergo scalding process

d. None of the above

Explanation: Rapid freezing prevents the formation of large ice crystals that cause "freezer burn" and oxidative darkening.

83. Tenderness of poultry meat can be maintained during cold storage by:

a. Storing it in aluminum foil

b. Storing it in plastic net

c. Storing it in unpacked

d. All of the above

Explanation: Packaging in moisture-vapor-proof materials like aluminum foil prevents dehydration and maintains texture.

84. It is the most popular refrigerant for air conditioning.

a. R-12 (Dichlorodifluoromethane)

b. R-22 (Monochlorodifluoromethane)

c. R-502 (Mixture of R-22 and R-115)

d. All of the above

Explanation: R-22 was historically the standard for AC units, though it is now being phased out for HFC alternatives.

85. Which of the following statements is true:

a. The motor and compressor of a refrigeration system is separately installed.

b. The motor and compressor of a refrigeration system is housed in the same compartment.

c. The compressor and the motor of a refrigeration system is non-hermetic type?

d. None of the above

Explanation: In domestic units, hermetic compressors house the motor and pump in a single sealed container to prevent leaks.

86. A newly discovered refrigerant that is not harmful for the ozone layer or referred to as “ozone friendly gas.”

a. R-12

b. Ammonia

c. Suva Mp 52 (R-134a)

d. All of the above

Explanation: R-134a is an HFC that has zero ozone depletion potential.

87. When heat is transmitted through molecular waves, it is transmitted by:

a. Convection

b. Conduction

c. Radiation

d. None of the above

Explanation: Radiation transmits energy through electromagnetic waves without requiring a medium.

88. The unit of energy in SI system is:

a. Newton-meter

b. Joules

c. W-sec.

d. All of the above

Explanation: A Joule is defined as a Newton-meter (N * m) or a Watt-second (W * s).

89. It is considered a refractory material:

a. Lime

b. Alumina

c. Silica

d. None of the above

Explanation: Silica is a primary refractory material used in lining high-temperature furnaces.

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