Module 9 Macq notes

 Murphy’s Law

1. There is a tendency among human beings towards
1. Complacency
2. which  belief can be a major problem
1. an accident will never happen to “me” or to “my Company
3. “Murphy’s Law” Can be regarded as the notion:
1.   “If something can go wrong, it will.”
2.  An accident will never happen to “me” or to “my Company

vision

1.  a light sensitive surface
1.  (the retina
2. the light-sensitive cells on the retina 
1. (rods and cones)
3. electrical impulses by way of the ____ to the visual cortex in the brain
1. optic nerve
4. The cornea is responsible for between 70% and 80% of the total focusing ability (refraction) of the eye.
5. The iris (the colored part of the eye) controls the amount of light.
6. The size of the pupil can be changed very rapidly to cater for
1.  changing light levels
2. The amount of light can be adjusted by a factor of 5:1.
7. The change of shape of the lens is called accommodation. 
8. Its shape is changed by the muscles (cillary muscles)
9. When a person is tired, accommodation is reduced, resulting in less sharp vision (sharpness of vision is known as visual acuity).
10.  The central area of the retina is known as the ___ and the receptors in this area are all ___.
1. fovea, cones
2.  cones, fovea
11. Cones are capable of detecting fine detail and are 
1. color-sensitive. 
2. The human eye can distinguish about 1000 different shades of color.
3. All
12. Rods cannot detect colour
1. poor at distinguishing fine detail, 
2. but good at detecting movement in the edge of the visual field (peripheral vision). 
3. Much more sensitive at lower light levels
4. All
13. This means in poor light levels we see 
1. only in black and white and shades of gray
2. 
   
14.  At the point at which the optic nerve joins the back of the eye, a ‘blind spot’ occurs
15. viewing things with both eyes (binocular vision),
16. viewing with one eye (monocular vision)
17. constant rapid movement of the eye (saccades) 
18. In maintenance engineering, tasks such as close visual inspection or crack detection should not cause such problems, as the eye or eyes move across and around the area of interest (visual scanning).
19. The eye has approximately
1.  1.2 million nerve cells leading
2.  from the retinas to the area of the brain responsible for vision, 
3. both
20.  only about 50,000 from 
1. the inner ears 
2.  making the eye about 24 times more sensitive than the ear.
3. Making the eye about 50 times more sensitive than the ear.
4. 1 and 2
21. Visual acuity is
1.  the ability of the eye 
2. to discriminate sharp detail at varying distances
3. both 1 and 2
22. Various factors can affect and limit the visual acuity of the eye. These include:
1.  Physical factors
2. The influence of ingested foreign substances
3. Environmental factors
4. Factors associated with object being viewed 
5. all the above 
23.  Long sight — known as 
1. Hypermetropia
2. myopia.
3.  The image is formed behind the retina
4.  1 and 3
24. Hypermetropia 
1. A convex lens is used to correct it
2. a concave lens is used to correct it 
25. Short sight — known as Myopia
1. Hypermetropia
2. myopia.
3.  The image is formed in front of the retina
4.  2 and 3
26. a concave lens is used for correct it 
1.  myopia 
2. Hypermetropia
27. cataracts — 
1. clouding of the lens,
2.  usually associated with aging;
3. both  
28.  astigmatism — 
1. A misshapen cornea 
2. causing objects to appear irregularly shaped; 
3. all
29.  glaucoma —
1.  a build up in pressure of the fluid within the eye 
2. which can cause damage to the optic nerve and even blindness
3. all
30.  migraine severe 
1. headaches 
2. that can cause visual disturbances.
3. All
31.  it is unable to accommodate sufficiently. This is known as,
1. presbyopia, and is a form of long-sightedness.
2.  After the age of 40,
3. both
32. With smoking, carbon monoxide which builds up in the bloodstream allows less oxygen to be carried in the blood to the eyes. This is known as,
1.  hypoxia,
2. cataracts
3. astigmatism 
33.   Eyes have become light adapted
1. Moving from an extremely bright environment to a dimmer one has the effect of vision being severely reduced until the eyes get used to less light being available.
2.  If an engineer works in a very dark environment for a long time, his eyes gradually become
3. about 7 minutes for the cones and 30 minutes for the rods
4. 1 and 3
34.   dark adapted allowing better visual acuity
1. If an engineer works in a very dark environment for a long time, his eyes gradually become
2. Moving from an extremely bright environment to a dimmer one has the effect of vision being severely reduced until the eyes get used to less light being available
35. Engineers who wear contact lenses  the maximum wear time - usually 
1. 8 to 12 hours 
36. Many factors associated with the object being viewed can also influence vision. We use information from the objects we are looking at to help distinguish what we are seeing. These are known as visual cues. 
37. Colour-defective vision affects about 
1.  8% of men
2. only 0.5% of women.
3. 0.6% of women 
4. 1 and 3 
38.  The most common type is difficulty in distinguishing 
1.  between red and green. 
2.  Blues and yellows.
3. Both

Hearing

1. the ear has three divisions: 
1. outer ear, middle ear and inner ear
2. The outer part of the ear 
1. Direct sounds down the auditory canal, and on to the eardrum.
3.  The middle ear which transmits vibrations from the eardrum by way of three small bones known as the
1.  ossicles
2. two muscles which help to protect the ear  from sounds above 80 dB 
3. the acoustic or aural reflex, reducing the noise level by up to 20 dB. 
4. All
4.  protection can only be provided for a maximum of about 
1. 15 minutes
2. 16 minutes
5. The middle ear is usually filled with air which is refreshed 
1. by way of the Eustachian tube 
2. which connects this part of the ear with the back of the nose and mouth. 
3. All
6. The last of the ossicles (3 bones)in the middle ear is connected
1.   to the cochlea.
2. This contains a fine membrane (the basilar membrane) 
3.  Which are sensitive to movement in the fluid.
4. All
7.  neural impulses to be transmitted to the brain via the auditory nerve.
8.  The amount of vibration detected in the cochlea depends on the volume and pitch of the original sound

Performance and Limitations of the Ear

1. The audible frequency range that a young person can hear is typically between
1. 20 and 20,000  Hertz with the greatest sensitivity at about 3000 Hz.
2. 20 and 30,000  Hertz with the greatest sensitivity at about 3000 Hz.
2. Noise can have various negative effects in the workplace. It can:
1.  be annoying, interfere with verbal communication between individuals in the workplace,
2.  cause accidents by masking warning signals or messages,  be fatiguing and affect concentration, decision-making, 
3.  damage workers’ hearing
4. all the above 
3. The degree of impairment is influenced mainly by the intensity of the noise. Such damage is known as,
1.  Noise Induced Hearing Loss (NIHL).
2.  
4. The combination of duration and intensity of noise can be described as
1.   noise dose
5. It is normally accepted that a TWA noise level exceeding 
1. 85 dB for 8 hours is hazardous and potentially damaging to the inner ear.
2.  115 decibels without ear protection, even for a short duration, is not recommended
3. both
6. Noise levels can be reduced (attenuated) by up to 
1. 20 decibels using ear plugs 
2. 40 decibels using ear muffs
3. both
7. Hearing deteriorates naturally as one grows older. This is known as presbycusis.
1. This affects ability to hear high pitch sounds first,
2. may occur gradually from the 30’s onwards.
3. both
8.