Module 11 Aero plane Aerodynamics, Structures & Systems Final Practice Exam

 

Module - 11 (Aeroplane Aerodynamics, Structures & Systems)

Final Practice Exam Test

  

 

1. If an aircraft is yawing to the left, where would you position the trim tab on the rudder ?
   1.   To the centre
   2.   To the right
   3.   To the left
2. When a leading edge flap is fully extended,what is the slot in the wing for?
   1.   To increase the lift
   2.   To re-energise the boundary layer
   3.   To allow the flap to retract into it when it retracts
3. The purpose of a slot in a wing is to ?
   1.   act as venturi, accelerate the air and re-energise boundary layer
   2.   speed up the airflow and increase lift
   3.   provide housing for the slat
4. Large flap deployment ?
   1.   causes increased spanwise flow towards tips on wing upper surface
   2.   causes increased spanwise flow towards tips on wing lower surface
   3.   has no effect on spanwise flow
5. In a Central Air Data Computer (ADC),Indicated Air Speed (IAS) is produced from ?
   1.   static pressure only
   2.   pitot pressure only
   3.   pitot and static air pressure
6. In a Central Air Data Computer, altitude is produced from ?
   1.   static air pressure
   2.   pitot pressure only
   3.   pitot and static air pressure
7. On a flight management system, the database is updated every ?
   1.   3 Month
   2.   1 Month
   3.   2 Month
8. On a modern aircraft flight instrument display system, Radio deviation is shown on ?
   1.   EADI
   2.   EHSI
   3.   EHSI & EADI
9. Which part of the wing of a swept-wing aircraft stalls first ?
   1.   Tip stalls first
   2.   Root stalls first
   3.   Both stall together
10. Extending a leading edge slat will have what effect on the angle of attack of a wing?
    1.   Increase the angle of attack
    2.   No effect on angle of attack
    3.   Decrease the angle of attack
11. Wing tip vortices are strongest when ?
    1.   flying slowly at high angles of attack
    2.   flying high speed straight and level flight
    3.   flying into a headwind
12. An example of a secondary flight control is a ?
    
    1.   elevator
    2.   flap
    3.   spoiler
13. When the trailing edge flaps are lowered, the aircraft will?
    
    1.   sink
    2.   pitch nose down
    3.   pitch nose up
14. On an aircraft with an all-moving tailplane pitch up is caused by ?
    1.   increasing tailplane incidence
    2.   decreasing tailplane incidence
    3.   up movement of the elevator trim tab
15. The layer of air over the surface of an aerofoil which is slower moving, in relation to the rest of the airflow, is known as?
    
    1.   boundary layer
    2.   camber layer
    3.   none of the above are correct
16. What is a controlling factor of turbulence and skin friction ?
    
    1.   Aspect ratio
    2.   Fineness ratio
    3.   Countersunk rivets used on skin exterior
17. Fuselage station numbers are measured from the front of the aircraft in ?
    1.   feet
    2.   inches
    3.   feet and inches
18. Structure with built in redundancy is called ?
    
    1.   failsafe
    2.   double safe
    3.   safe life
19. The Airworthiness Notice that refers to structural surveys is ?
    
    1.   Notice 65
    2.   Notice 79
    3.   Notice 89
20. Wrinkling of the skin on the upper surface of the fuselage indicates ?
    
    1.   sagging
    2.   shedding
    3.   hogging
21. A structure that has a high designed reserve strength would be classified as ?
    
    1.   secondary
    2.   tertiary
    3.   primary
22. In semi-monocoque construction, compression loads are taken by ?
    
    1.   bulkheads
    2.   stringers
    3.   frames
23. Buckling in a semi-monocoque structure is prevented by ?
    
    1.   longerons.
    2.   bulkheads
    3.   stringers
24. When both sides of a structural repair are not easily reached, which type of fastener would you use ?
    
    1.   Pop rivet
    2.   Blind rivet
    3.   Hi lock bolt
25. If an aircraft has alkaline batteries, the battery compartment drain pipes will be ?
    
    1.   plastic
    2.   aluminium alloy
    3.   stainless steel
26. When an item is cocooned, the visual indicator will indicate ?
    1.   humidity
    2.   temperature
    3.   toxic gases
27. Wing bending and shear loads are taken by ?
    1.   spar cap
    2.   main spar
    3.   skin
28. A leading edge slat is attached to the ?
    1.   slat track
    2.   wing upper skin
    3.   front spar
29. Flutter can be reduced by using ?
    1.   servo tabs
    2.   a horn balance
    3.   mass balancing
30. An elevator controls the aircraft motion in ?
    1.   yaw
    2.   pitch
    3.   roll
31. When does a 'blower' air conditioning system produce the most air ?
    
    1.   At high altitudes
    2.   At low altitudes
    3.   It is not affected by altitude
32. When an aircraft is heading due north (magnetic) towards a VOR station the reference and variable signals will be ?
    1.   270° out of phase
    2.   in phase
    3.   180° out of phase
33. The modulation of the outer marker is ?
    1.   400 Hz
    2.   1300 Hz
    3.   3000 Hz
34. The approximate distance of the middle marker from the runway threshold is ?
    1.   3 miles
    2.   3500 ft
    3.   7 miles
35. The VOR system comprises ?
    1.   reference phase signal
    2.   variable phase signal
    3.   variable and reference phase signals
36. The glideslope transmitter operates on ?
    1.   frequencies of 108 to 118 MHZ
    2.   the UHF band
    3.   the VHF band
37. L band DME transmits on a frequency of ?
    1.   1090 MHz
    2.   2210 MHz
    3.   4133 MHz
38. Laser gyros have ?
    1.   2 rotating parts
    2.   4moving parts
    3.   no rotating parts
39. Flight management control system (FMCS) utilises ?
    1.   VOR, ADF, DME
    2.   ILS, DME, ADC
    3.   ILS, VOR, ADF
40. What channel of the autopilot does the glideslope control?
    1.   Pitch
    2.   Roll
    3.   Yaw
41. Radio marker information is displayed on ?
    1.   ADI
    2.   EICAS
    3.   HIS
42. Where is alpha angle used ?
    1.   IRS
    2.   Accelerometer
    3.   Angle of attack
43. In Airways flying, what is the barometric scale of the altimeter set to ?
    1.   2000.25
    2.   1013.25
    3.   100.25
44. The hot junction of thermocouple is ?
    1.   in the combustion chamber
    2.   in the instrument
    3.   aft of combustion chamber
45. What kind of gyro is a rate gyro ?
    1.   Displacement
    2.   Tied down
    3.   Space
46. When carrying out a symmetry check on a large aircraft, what method of measurement is normally used?
    1.   Lateral alignment method
    2.   Longitudinal alignment method
    3.   Steel tape and spring balance
47. What are the faying surfaces of a repair?
    1.   Middle of repair
    2.   Material under repair
    3.   Edges of repair metal
48. Why is a joggle joint used?
    1.   To provide a flush fit
    2.   To provide a smooth contour to surface
    3.   To add strength
49. DME works on the frequency of ?
    1.   HF
    2.   UHF
    3.   VHF
50. GPS uses ?
    1.   uses 21 satellites equally spaced around 7 orbits
    2.   uses 18 satellites equally spaced around 6 orbits
    3.   uses 24 satellites equally spaced around 6 orbits
51. Decca navigation uses ?
    1.   LF
    2.   HF
    3.   VHF
52. Earth rate is approximately ?
    1.   5 degrees per hour
    2.   15 degrees per hour
    3.   84 degrees per hour
53. The localizer deviation signal for the flight director comes from the ?
    1.   flight director computer
    2.   VHF comm system
    3.   VHF nav system
54. The preferred method of battery charging a Ni-Cad battery is constant ?
    1.   current
    2.   power
    3.   voltage
55. What does the differential sensing coil sense ?
    1.   Power
    2.   Volts
    3.   Current
56. In an AC generation system, the frequency and phase rotation ?
    1.   must be out of phase prior to paralleling
    2.   is of no consequence after paralleling
    3.   must be synchronized prior to paralleling
57. One of the main purposes of a CSD is to ?
    1.   maintain constant load on the generator
    2.   enable generators to be paralleled
    3.   prevent engine overload
58. What is the small pin on the DC ground power connector ?
    1.   Positive to external power relay
    2.   Positive to battery relay
    3.   Ground or earth
59. How is RAT driven ?
    1.   Fan
    2.   Compressor
    3.   Airstream
60. The small pins in the power connector plug are ?
    1.   positive
    2.   negative
    3.   neutral
61. Zener diodes are for ?
    1.   rectification
    2.   voltage stabilization
    3.   voltage regulation
62. Which components within a generator control unit connects the output of the field power supply to the generator exciter?
    1.   Generator control relay
    2.   Generator line contactor
    3.   Generator power pilot relay
63. During normal engine shut-down, the generator ?
    1.   breaker and control relay are both tripped
    2.   control relay is tripped only
    3.   breaker is tripped only
64. A neutralizing agent for sulphuric acid is ?
    1.   sodium bicarbonate
    2.   borax powder
    3.   citric acid
65. A vibrating contact voltage regulator has ?
    1.   a resistor in series with the points
    2.   a volts coil in parallel with the points
    3.   a resister in parallel with the points
66. The method used to rapidly charge a nickel-cadmium battery utilizes ?
    1.   constant current and varying voltage
    2.   constant voltage and varying current
    3.   constant current and constant voltage
67. A constant speed drive unit has a warning light indication ?
    1.   for low speed
    2.   for low oil pressure
    3.   for when it is disconnected from the generator
68. The purpose of an inverter is to convert ?
    1.   DC to AC
    2.   AC to DC
    3.   AC to a higher frequency AC
69. The electrolyte in a lead-acid battery contains ?
    1.   hydrochloric acid
    2.   nitric acid
    3.   sulphuric acid
70. To prevent corrosion at the terminals of a lead-acid battery ?
    1.   copper connectors are used
    2.   petroleum jelly may be applied to the connections
    3.   the connectors may be painted
71. The output from an AC generator is taken from ?
    1.   slip rings
    2.   slip rings via commutator
    3.   connections on the stator
72. When connecting aircraft batteries, the last lead to connect is the ?
    1.   positive earth
    2.   negative
    3.   positive
73. In a paralleled AC generation system load sharing is for ?
    1.   real and reactive load
    2.   reactive load only
    3.   real load only
74. The ratio between apparent power and true power is the ?
    1.   efficiency
    2.   power factor
    3.   power rating
75. Apparent power is measured in ?
    1.   Volt Amps
    2.   Kilovolts
    3.   Watts
76. Cargo and baggage compartments in which a fire is completely confined come under ?
    1.   Class B
    2.   Class C
    3.   Class D
77. Aircraft emergency escape slides are usually pressurised with ?
    1.   oxygen
    2.   CO2
    3.   helium
78. How do you clean seat belts ?
    1.   With MEK
    2.   With white spirit
    3.   With warm water with low alkalinity soap
79. Megaphones must be stowed so they can withstand an inertia force of ?
    1.   9g
    2.   12g
    3.   15g
80. Cargo nets are manufactured from ?
    1.   nylon
    2.   hessian
    3.   polypropylene
81. Toilet flush motor is protected from overheat by ?
    1.   water cooling
    2.   thermal protection
    3.   cooling fan on timer switch
82. What type of compressor is used on a pneumatic system ?
    1.   Rotary vane type
    2.   Spur gear type
    3.   Positive displacement type
83. High pressure pneumatic pump is a ?
    1.   spur gear
    2.   butterfly pump
    3.   reciprocating pump
84. The pneumatic system pump is a ?
    1.   centrifugal type
    2.   rotor vane type
    3.   piston type
85. To check an oxygen system for moisture ?
    1.   a sniff test is used
    2.   a hygrometer is used
    3.   pass 72 litres/min through a filter paper in a clean glass
86. Oxygen purging is a process of ?
    1.   pressure testing the system
    2.   measuring the flow rate from the regulator
    3.   removing moisture from the system
87. Lubricate oxygen connector threads using ?
    1.   Teflon tape
    2.   Hellerene
    3.   WD40
88. A chemical oxygen generator operates at ?
    1.   45°C at 10 psi for 15 minutes
    2.   45°F at 10 psi for 15 minutes
    3.   45°K at 10 psi for 15 minutes
89. Cylinders containing purified oxygen for breathing are painted ?
    1.   black with a white collar
    2.   black
    3.   white with a black collar
90. The international marking for a breathing oxygen pipeline is a series of ?
    1.   dots
    2.   rectangles
    3.   diamonds
91. An anti-balance tab is used ?
    1.   to give more feel to the controls
    2.   for trimming the aircraft
    3.   to relieve stick loads
92. Oxygen filters are made of ?
    1.   carbon fibres
    2.   steel wool
    3.   sintered bronze
93. The direction of flow in an oxygen non return valve is indicated ?
    1.   by visual inspection
    2.   by colour coding
    3.   by an arrow
94. To avoid condensation forming in an oxygen cylinder ?
    1.   cylinder pressure is left at 100/200 p.s.i.
    2.   cylinder pressure is left at 200/300 p.s.i.
    3.   cylinder pressure is left at 300/400 p.s.i.
95. Oxygen bottle capacity varies between ?
    1.   80 2250 litres
    2.   100 3200 litres
    3.   200 2250 litres
96. Oxygen cylinders are removed for overhaul and tested ?
    1.   every 3 years
    2.   every 6 years
    3.   every 4 years
97. Rate of flow of oxygen is given in ?
    1.   pounds/minute
    2.   litres/pounds
    3.   litres/minute
98. The cylinder of a portable oxygen set is made of ?
    1.   aluminium
    2.   alloy steel
    3.   stainless steel
99. Pressure breathing systems must be used at altitudes ?
    1.   above 40,000 ft
    2.   below 40,000 ft
    3.   above 30,000 ft
100. The critical altitude for oxygen requirement is approximately ?
     1.   38,000 ft
     2.   25,000 ft
     3.   4,000 ft
101. A chemical oxygen generator has a supply duration of at least ?
     1.   15 minutes
     2.   30 minutes
     3.   5 minutes
102. The life of an aircraft oxygen cylinder is ?
     1.   2 years
     2.   10 years
     3.   5 years
103. How do oxygen cylinders show over pressure ?
     1.   Green rupturing disc
     2.   Audible warning
     3.   Red rupturing disc
104. Where are the left handed threads found in an oxygen system ?
     1.   Line valve
     2.   Shut-off valve
     3.   Charging connection
105. A thermal compensator is used in ?
     1.   a fuel system
     2.   an oxygen system
     3.   an hydraulic system
106. What pressure are oxygen cylinders usually pressurised to ?
     1.   300 PSI
     2.   1800 PSI
     3.   3000 PSI
107. Which connector has a left hand thread ?
     1.   N2
     2.   Freon
     3.   O2
108. A demand regulator in a portable oxygen bottle opens ?
     1.   all the time
     2.   when breathing
     3.   when 100% selected
109. Anoxia is due to ?
     1.   lack of oxygen
     2.   low air pressure on the body
     3.   release of nitrogen bubbles in the blood
110. Navigation lights are supplied by the following circuit ?
     1.   Dual circuit
     2.   Single circuit
     3.   Individual circuits
111. Wing tip vortices are strongest when ?
     1.   flying high speed straight and level flight
     2.   flying slowly at high angles of attack
     3.   flying into a headwind
112. Krueger flaps are on ?
     1.   the leading edge
     2.   the trailing edge
     3.   either the leading or training edge
113. In an Artificial Horizon, Erection Error is caused by ?
     1.   bottom lightness of inner gimbals
     2.   bottom heaviness of inner gimbals
     3.   displacement of erection control device
114. Machmeters work on ?
     1.   static
     2.   pitot
     3.   pitot and static
115. Emergency frequency is ?
     1.   125.5 Hz
     2.   121.5 Hz
     3.   123.5 Hz
116. Wavelength of band radar is ?
     1.   3 cm
     2.   5 cm
     3.   10 cm
117. CAT 2 RVR limit is ?
     1.   1200 ft
     2.   10,000 ft
     3.   1000 ft
118. Speed of an HMG is controlled by a ?
     1.   CSD unit
     2.   ID unit
     3.   Swashplate
119. The purpose of a synchronising bus bar is ?
     1.   to allow monitoring and trimming from the flight deck
     2.   to enable two propeller systems to be synchronised
     3.   to monitor total current load
120. Battery charging procedures can be found in ATA ?
     1.   Chapter 24 Section 21
     2.   Chapter 31 Section 21
     3.   Chapter 24 Section 31
121. A water separator is located ?
     1.   downstream of heat exchanger
     2.   downstream of turbine
     3.   upstream of the turbine
122. Air exiting the compressor side of an ACM ?
     1.   will have decreased pressure and temperature
     2.   no change in temperature or pressure as it is a centrifugal compressor
     3.   will have increased pressure and temperature
123. A gyroscopic body has its rigidity increased by ?
     1.   increasing the rotor speed
     2.   decreasing the rotor speed
     3.   decreasing the mass of the rotor
124. Random drift of a gyro is caused by ?
     1.   rotation of the earth
     2.   unbalance and bearing friction in the gyro
     3.   aircraft turning with an error in roll
125. On an aircraft's navigation displays, distance measuring equipment gives ?
     1.   ground range to beacon
     2.   slant range to beacon
     3.   height and range to beacon
126. The advantage of leading edge fluid de-icing is ?
     1.   aerodynamic shape is not disturbed
     2.   less of a fire hazard
     3.   more efficient
127. The force exerted by a hydraulic cylinder is equal to ?
     1.   area * volume
     2.   pressure * stroke
     3.   area * pressure
128. Phosphate Ester hydraulic fluid requires which kind of seals ?
     1.   Butyl Rubber
     2.   Synthetic Rubber
     3.   Natural Rubber
129. Mechanical sequence valves are operated by ?
     1.   a striker pin
     2.   the pilot
     3.   the operation of a NRV
130. How do you remove air from hydraulic fluid ?
     1.   Vent to atmosphere
     2.   Pass through a restriction
     3.   Pass over a tray
131. What happens to hydraulic fluid when it is overheated ?
     1.   Increase acidity
     2.   Increase viscosity
     3.   Increase alkalinity
132. When a fuel jettison valve is in transit, the magnetic indicator would show ?
     1.   amber and cross line
     2.   amber and in line
     3.   green and in line

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What is AMEL (Aircraft Maintenance Engineer License) ?

     In aviation, AMEL stands for Aircraft Maintenance Engineer License, and its types typically align with the categories of aircraft and their systems. 

    AMEL Categories

• Category A (Mechanic): Basic maintenance tasks on an aircraft.

• A1: Turbine-powered airplanes.
• A2: Piston-powered airplanes.
• A3: Turbine-powered helicopters.
• A4: Piston-powered helicopters.

• Category B (Technician/Engineer): Licensed to perform and certify complex tasks.

• B1: Mechanical (structures, engines, systems).
• B1.1: Turbine airplanes.
• B1.2: Piston airplanes.
• B1.3: Turbine helicopters.
• B1.4: Piston helicopters.

• B2: Avionics (electrical and electronic systems).

• Category C (Certifying Staff): Supervisory-level certification for aircraft maintenance tasks on large aircraft.

Requirements for AMEL

1. Educational Background:

   • Typically requires a high school diploma or equivalent, with a strong foundation in mathematics, physics, and English.

2. Approved Training Program:

   • Completion of an EASA Part-147 approved course or equivalent recognized training program.

3. Practical Experience:

• Without Training Course:  At least 5 years of practical experience in helicopter maintenance.
• With Training Course:    A minimum of 2 years of practical experience in the same field.

4. Knowledge Examinations:

   • Passing the required module exams based on the EASA syllabus.

5. Skill Assessment:

   • Demonstrating competency in practical tasks under the supervision of a licensed certifying engineer.

6. Medical Fitness:

• Meeting medical fitness standards for the aviation industry.

Steps to Obtain AMEL

1. Enroll in a Training Program:

   • Join an approved training institution that offers the syllabus.

2. Pass the Module Exams:

   • Successfully complete the written examinations for all required modules.

3. Gain Practical Experience:

   • Work on Aircraft to acquire the necessary experience. This must be documented inn logbook and verified by a licensed engineer.
   • Without Training Course:  At least 5 years of practical experience in helicopter maintenance.
   • With Training Course:    A minimum of 2 years of practical experience in the same field.

4. Apply for the License:

   • Submit your application to the aviation authority with all necessary documentation, including exam results and practical experience.

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Aircraft Basic Definitions

 Aircraft Basic Definitions  

Aircraft:  A machine that can fly, such as an airplane or helicopter.

Aerodynamics: The study of how air moves around objects, especially aircraft.

Aileron: A hinged surface on the wing that controls roll movement.

Altitude: The height of an aircraft above the ground or sea level.

Airfoil: A shape designed to produce lift when air flows over it.

Attitude: The orientation of an aircraft in relation to the horizon.

Chord Line: A straight line connecting the leading and trailing edges of a wing.

Drag: The force that resists the motion of an aircraft through the air.

Elevator: A control surface on the tail that adjusts the aircraft's pitch.

Flaps:  Movable surfaces on the wing that increase lift or drag.

Fuselage: The main body of an aircraft, where passengers and cargo are carried.

Landing Gear: The wheels or skids that allow an aircraft to land and take off.

Lift: The force that keeps an aircraft in the air, created by airflow over the wings.

Propeller: A rotating blade that generates thrust to move an aircraft forward.

Rudder: A control surface on the tail that controls yaw movement.

Stall: A condition where the wing stops generating enough lift due to a high angle of attack.

Thrust: The forward force produced by an engine or propeller.

Torque: A twisting force, often produced by an engine, that affects aircraft stability.

Turbulence: Irregular air movement that causes an aircraft to shake or move unpredictably.

Yaw: The side-to-side movement of an aircraft's nose, controlled by the rudder.

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Module 9 Human Factors Final Practice Exam (20 Questions 25 Mints)

 

Module - 9 (Human Factors)

Final Practice Exam Test

  

 

1. Which part of the body is responsible for spatial orientation in flight ?
   1.   Lungs
   2.   Heart
   3.   Inner ear
2. What has a great impact on the safety practices of workplace?
   1.   Safety culture
   2.   Organizational culture
   3.   Motivation
3. What do you do when someone is hypothermic ?
   1.   Warm them up
   2.   Feed them sweet things because of their diabetes
   3.   Give them a drink because of dehydration
4. What is the effect of alcohol on pilot performance ?
   1.   Has no effect if consumed in small amounts
   2.   Impairs judgment and reaction time
   3.   Improves coordination
5. Which of the following can help prevent human errors in aviation ?
   1.   Ignoring fatigue
   2.   Relying solely on automation
   3.   Following standard operating procedures
6. Which statement is true regarding avoiding and managing errors ?
   1.   Increase the error vulnerability of particular tasks or task elements
   2.   Decrease the error tolerance of a workplace or system
   3.   Minimize the error liability of the individual or team
7. An engineer is performing a task in less than ideal conditions in order to meet an operational deadline is ?
   1.   making a rule based slip
   2.   committing a situational violation
   3.   committed a routine error
8. What is a latent failure ?
   1.   A failure which could not have been predicted
   2.   Receiving bad instruction from a manager who is out of touch with maintenance
   3.   A mistake that has already been made, but has not yet caused an accident
9. What part of the SHEL model would the aircraft design fit into ?
   1.   Hardware
   2.   Liveware
   3.   Environment
10. The ear is sensitive to sounds between certain frequencies ?
    1.   20 khz to 2000 khz
    2.   20 hz to 200 khz
    3.   20 hz to 20000 hz
11. Environmental stresses are ?
    1.   caused by noise, fumes, heat and vibration
    2.   tolerated by everyone equally
    3.   not normally cumulative
12. How does dehydration affect pilot performance ?
    1.   Improves cognitive function
    2.   Enhances reaction time
    3.   Causes fatigue and poor concentration
13. Which of the following is an example of complacency in aviation ?
    
    1.   Asking for assistance when needed
    2.   Ignoring warning signs due to overconfidence
    3.   Carefully checking instruments
14. What is the primary purpose of Crew Resource Management (CRM) ?
    1.   Train pilots to fly faster
    2.   Improve teamwork and decision-making
    3.   Reduce aircraft maintenance costs
15. Which type of fatigue occurs after long-term stress or workload ?
    1.   Chronic fatigue
    2.   Acute fatigue
    3.   Temporary fatigue
16. For a man to maintain his fitness and health the conducive maximum recommended alcohol intake is ?
    1.   9 - 14 units per month
    2.   28 units per day
    3.   28 units per week
17. Which of the following is a sign of hypoxia ?
    1.   Enhanced memory
    2.   Impaired judgment
    3.   Increased alertness
18. Motivation is ?
    
    1.   The thing that drives someone to do something
    2.   A reward or punishment designed to increase work rate
    3.   A reward or punishment designed to reduce errors
19. Myopia is _______ and a ______ lens is needed to correct it ?
    1.   long sightedness and concave
    2.   short sightedness and convex
    3.   short sightedness and concave
20. How many things can be stored in the short term memory ?
    
    1.   9 - 15
    2.   3 - 5
    3.   No limit

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