Lecture 14 - Human Factors 2

Question 1

Light is an _________ wave.

Answer 1

electromagnetic

Question 2

________ is perceived as brightness.

Answer 2

Amplitude

Question 3

___________ is perceived as hue.

Answer 3

wavelength

Question 4

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

Answer 4

refraction

Question 5

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

Answer 5

1

Question 6

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

Answer 6

59

Question 7

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

Answer 7

Pupil

Question 8

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

Answer 8

increase

Question 9

What is fatiguing about accommodation?

Answer 9

Contraction of ciliary muscle

Question 10

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

Answer 10

suspensory ligaments

Question 11

_______ = far objects are blurry

Answer 11

myopia

Question 12

_______ = near objects blurry

Answer 12

hypermetropia

Question 13

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

Answer 13

Astigmatism

Question 14

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

Answer 14

spherical abberation

Question 15

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

Answer 15

close

Question 16

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.

Answer 16

red; bleaching

Question 17

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

Answer 17

Purkinje Shift; green; red

Question 18

Is night or day vision more sensitive?

Answer 18

Night

Question 19

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

Answer 19

yellowish-green; green

Question 20

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

Answer 20

melatonin

Question 21

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

Answer 21

melanopsin

Question 22

One _____ = one lumen per square meter.

Answer 22

lux

Question 23

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

Answer 23

1

Question 24

What are the 5 main causes of lighting problems?

Answer 24

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

Question 25

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

Answer 25

decreases

Question 26

What are the two types of glare?

Answer 26

1. Direct | 2. Indirect

Question 27

What are the two types of indirect glare?

Answer 27

1. Specular (smooth) | 2. Diffuse (matte)

Question 28

What are the 3 effects of glare?

Answer 28

1. Discomfort 2. Disability 3. Blinding

Question 29

_______ = natural tendency to gaze at bright objects.

Answer 29

Phototropism

Question 30

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

Answer 30

120

Question 31

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

Answer 31

50

Question 32

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

Answer 32

presbyopia

Question 33

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

Answer 33

Myopia

Question 34

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

Answer 34

hypermetropia

Question 35

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

Answer 35

0.15

Question 36

Natural distance where _______ becomes necessary changes with gaze angle.

Answer 36

vergence

Question 37

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

Answer 37

1m; 80 cm

Question 38

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

Answer 38

more

Question 39

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

Answer 39

accommodation

Question 40

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

Answer 40

20; 40

Question 41

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

Answer 41

scotopic; photopic; mesopic

Question 42

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

Answer 42

blue and yellow

Question 43

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

Answer 43

luminous flux

Question 44

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

Answer 44

illuminance

Question 45

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

Answer 45

luminance

Question 46

What are 5 common health effects associated with poor lighting?

Answer 46

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

Question 47

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

Answer 47

specular

Question 48

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

Answer 48

diffuse

Question 49

What are 3 ways to decrease display refection?

Answer 49

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

Question 50

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

Answer 50

glare

Question 51

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

Answer 51

vertically

Question 52

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

Answer 52

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

Question 53

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

Answer 53

name