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