Section 16.1
Illumination
Practice Test
1.
In Figure 16-4, if
r
is decreased to 0.25 m, what will be the total luminous flux striking the inside of the sphere?
a.
7000 lm
b.
875 lm
c.
1750 lm
d.
438 lm
Hint
2.
A ray of light travels in a __________.
a.
straight line
b.
curved line
c.
back-and-forth motion
d.
circle
Hint
3.
__________ is the speed of light defined.
a.
c
b.
a
c.
e
d.
d
Hint
4.
Danish astronomer Ole Roemer first measured the speed of light by studying __________.
a.
how lasers travel in space
b.
the Moon
c.
how light traveled around two mountains
d.
the orbit of Io, a moon of Jupiter
Hint
5.
In Figure 16-4, if
r
is decreased to 0.25 m, what will be the illuminance of the sphere?
a.
2224 lx
b.
8.69 lx
c.
139 lx
d.
556 lx
Hint
6.
In Figure 16-6, if the candle were moved so that it was 2
d
to the right of the screen, but the lamp was not moved, how would the luminous intensity of the lamp have to be adjusted to make each side of the screen equally illuminated?
a.
It would need to be quartered.
b.
It would need to be doubled.
c.
It would need to be halved.
d.
It would need to be quadrupled.
Hint
7.
The two main factors affecting the illuminance of an object are __________.
a.
distance and hardness
b.
hardness and color
c.
color and brightness
d.
distance and brightness
Hint
8.
__________ is the rate at which light falls on a surface.
a.
Fluorescence
b.
Illuminance flux
c.
Luminous flux
d.
Illuminance
Hint
9.
__________ is the rate at which visible light is emitted from an object.
a.
Luminous flux
b.
Illuminated flux
c.
Amplitude flux
d.
Frequency flux
Hint
10.
What did Roemer prove?
a.
the correct speed of light
b.
light travels instantaneously
c.
light has no speed
d.
light travels at a finite speed
Hint
11.
In Figure 16-6, if the candle were moved so that it was
d
/2 to the right of the screen, but the lamp was not moved, how would the luminous intensity of the lamp have to be adjusted to make each side of the screen equally illuminated?
a.
It would need to be quadrupled.
b.
It would need to be doubled.
c.
It would need to be halved.
d.
It would need to be quartered.
Hint
12.
Illuminance __________ as the light source moves away from the object.
a.
increases with an inverse relationship
b.
decreases with an inverse relationship
c.
increases with an inverse square relationship
d.
decreases with an inverse square relationship
Hint
13.
A(n) __________, like the Moon, reflects light.
a.
reflecting body
b.
radiating body
c.
laminated body
d.
illuminated body
Hint
14.
A medium that allows light to pass through but does now allow the light source to be visible is__________.
a.
transgressant
b.
transparent
c.
opaque
d.
translucent
Hint
