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EPHE 456 > Lecture 14 - Human Factors 2 > Flashcards

Lecture 14 - Human Factors 2 Flashcards

1
Q

Light is an _________ wave.

A

electromagnetic

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2
Q

________ is perceived as brightness.

A

Amplitude

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3
Q

___________ is perceived as hue.

A

wavelength

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4
Q

________ is the change in direction of propagation of a wave due to a change in its transmission medium

A

refraction

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5
Q

A lens that can focus parallel light rays to a point 1 meter from its axis has a refractive power of ____ diopter.

A

1

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6
Q

Our eyes have a refractive power of ____ diopters when viewing distant objects.

A

59

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7
Q

The _______ contracts and expands to adjust the amount of light entering the eye.

A

Pupil

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8
Q

To focus for near objects we need to (increase/decrease) the refractive power of the lens.

A

increase

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9
Q

What is fatiguing about accommodation?

A

Contraction of ciliary muscle

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10
Q

When the muscle is relaxed, the _______ ________ pull the lens back into a thinner flatter shape.

A

suspensory ligaments

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11
Q

_______ = far objects are blurry

A

myopia

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12
Q

_______ = near objects blurry

A

hypermetropia

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13
Q

_________ = refractive error due to an unequal curvature of the refractive surface (either cornea or lens)

A

Astigmatism

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14
Q

________ ________ = outer regions of the lens focus light at a point slightly ahead of the mid portion of the lens, causing vision to be blurred.

A

spherical abberation

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15
Q

Objects that are very _______ require muscle contraction to enable the eyes to converge (and focus via accommodation) on the object.

A

close

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16
Q

Since we are least sensitive to ______ we can illuminate a room or sign with this colour and not worry about _______ out our ability to see in dark environments.

A

red; bleaching

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17
Q

_______ _____ = as we switch from cone to rode vision (day to night) shorter wavelengths appear brighter (_____ objects appear brighter, _____ objects appear darker).

A

Purkinje Shift; green; red

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18
Q

Is night or day vision more sensitive?

A

Night

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19
Q

Our most sensitive light ranges are _______-_____ light during daylight and _______ light at night.

A

yellowish-green; green

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20
Q

Blue light affects levels of the sleep-inducing hormone ________ more than any other wavelength.

A

melatonin

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21
Q

Retinal ganglion cells contain _______ which is sensitive to blue light and can modify your circadian rhythm.

A

melanopsin

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22
Q

One _____ = one lumen per square meter.

A

lux

23
Q

A common candle emits light with roughly ___ cd luminous intensity.

A

1

24
Q

What are the 5 main causes of lighting problems?

A
  1. Insufficient light
  2. Glare
  3. Improper contrast
  4. Poor distribution
  5. Flicker
25
Q

Performance time _____ with increasing amount of illumination, and error _____ as well.

A

decreases

26
Q

What are the two types of glare?

A
  1. Direct

2. Indirect

27
Q

What are the two types of indirect glare?

A
  1. Specular (smooth)

2. Diffuse (matte)

28
Q

What are the 3 effects of glare?

A
  1. Discomfort
  2. Disability
  3. Blinding
29
Q

_______ = natural tendency to gaze at bright objects.

A

Phototropism

30
Q

Lamps operating on alternating current produce light flickering at a frequency of ______ Hz.

A

120

31
Q

People can see lights flashing on and off up to about ____ flashes per second (____ Hz)

A

50

32
Q

_______ = accommodation decreasing with age, to the point where we can’t anymore.

A

presbyopia

33
Q

With _______, light is focused in front of the retina, and it is corrected with a concave lens.

A

Myopia

34
Q

With ______, light is focused behind the retina, and it is corrected with a convex lens.

A

hypermetropia

35
Q

The typical eye has +0.__ microns of spherical aberration.

A

0.15

36
Q

Natural distance where _______ becomes necessary changes with gaze angle.

A

vergence

37
Q

What distance should an object be when looking ahead? When looked 45 degrees down?

A

1m; 80 cm

38
Q

We have (more/less) accommodative power when we gaze downwards.

A

more

39
Q

Objects right at point of _______ will cause constant adjustments rendering them in and out of focus.

A

accommodation

40
Q

A person with 20/40 vision can detect a critical detail at ___ feet that a normal person could detect at ____ feet.

A

20; 40

41
Q

Night vision = ______; day vision = ______; dusk vision = _______.

A

scotopic; photopic; mesopic

42
Q

Protanopia and deuteranopia = seeing in shades of what two colours?

A

blue and yellow

43
Q

_______ _____ (cd)= total light emitted by a source.

A

luminous flux

44
Q

________ (Lm/m^2) = light falling onto a surface

A

illuminance

45
Q

_________ (cd/m^2) = light reflected by a surface

A

luminance

46
Q

What are 5 common health effects associated with poor lighting?

A
  1. Headache and eyestrain
  2. Neck, back and shoulder strain
  3. Falling tripping and slipping
  4. dropping materials and tools
  5. Depression
47
Q

With _______ reflection, viewer sees a reflection at only one point.

A

specular

48
Q

With _____ reflection, lights from all points on the surface reach the viewer.

A

diffuse

49
Q

What are 3 ways to decrease display refection?

A
  1. Blinds
  2. Indirect lighting systems
  3. Low wattage direct light on documents
50
Q

When light hits a flat surface, some of it becomes horizontally polarized with causes ______.

A

glare

51
Q

Only safe, _______ polarized light passes through specially treated polarized sunglass lenses.

A

vertically

52
Q

What is a way to combat the headaches, eyestrain and general eye discomfort reported by people working in fluorescent lighting?

A

use a high frequency electronic ballast of 20,000 Hz or higher

53
Q

With colour and perception, we basically can only identify the colours we can ______.

A

name

EPHE 456 (12 decks)

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