Section 18.2
Convex and Concave Lenses
Practice Test
1.
The refractive indices of lenses are __________.
a.
greater than air
b.
less than air
c.
independent of the refractive index of air
d.
the same as air
Hint
2.
An achromatic lens corrects chromatic aberration using __________.
a.
no lenses
b.
two concave lenses with the same index of refraction
c.
a combination of concave and convex lenses with different indices of refraction
d.
two convex lenses with the same index of refraction
Hint
3.
A concave lens is also known as a __________ lens.
a.
converging
b.
diverging
c.
plane
d.
concave
Hint
4.
Why are bigger lenses better for observing dim objects?
a.
they have better curvatures
b.
they collect more light
c.
they refract light less
d.
they reduce spherical aberration
Hint
5.
In Figure 18-11, if the top half of the lens is covered, what will happen to the image?
a.
Nothing.
b.
The top half of the image will disappear.
c.
The bottom half of the image will disappear
d.
The image will become dimmer.
Hint
6.
In Figure 18-11, if the bottom half of the lens is covered, what will happen to the image?
a.
The top half of the image will disappear.
b.
Nothing.
c.
The image will become dimmer.
d.
The bottom half of the image will disappear
Hint
7.
Unlike mirrors, lenses have __________.
a.
two focal points
b.
many focal points
c.
no focal points
d.
one focal point
Hint
8.
An image of a flower is seen through a lens. What is the object?
a.
a flower
b.
a mirror
c.
a lens
d.
an image
Hint
9.
The focal length of a concave lens is __________.
a.
negative
b.
magnified
c.
positive
d.
reduced
Hint
10.
__________ single lenses have chromatic aberration.
a.
Only convex
b.
Only concave
c.
Only parabolic
d.
All
Hint
11.
In Figure 18-13, if you wanted to make the virtual image larger, what could you do?
a.
Replace the lens with a taller one.
b.
Move the object further out, but not past the focal point.
c.
Replace the object with a shorter object.
d.
Replace the lens with one of larger focal length.
Hint
