Mirrors Study guide ANSWER KEY
Vocabulary: see notes
1.
2.
3.
4.
5.
6.
7.
8.
Law of Reflection
Specular or planar reflection
Diffuse reflection
Luminous
Illuminated
Incident ray
Reflected ray
Normal
9. Concave mirror
10. Plane mirror
11. Convex mirror
12. Virtual image
13. Real image
14. Angle of incidence
15. Angle of reflection
16. Ray diagram
Light characteristics:
1.
2.
3.
4.
5.
In order for light to form it must be _reflected_________ back to the eye.
Light travels in __straight__________ lines.
When you look at an object, the light is reflected back along a _line_______ of _sight____________.
Since light rays converge on a __concave______ mirror, it is also called a _converging______ mirror.
Since light rays diverge on a __convex_______ mirror, it is also called a ___diverging___________ mirror.
Diagrams:
Label the following as either specular or diffuse reflection:
Specular
Diffuse
Label the following concave mirror with the following:
Principal axis, center of curvature, vertex, focal point, radius, focal length
Label as either a concave or convex mirror:
Convex
Concave
Real (R) vs. Virtual Images (V)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
_V____ Are upright
_R____ Are inverted
_V____ Are behind the mirror
__R___ Are on the same side of the mirror as object
_R, V____ Are formed by concave mirrors
_V____ Are formed by convex mirrors
_R____ Can be projected onto a screen
_R____ Rays of light actually converge and pass through the image
_V____ Rays of light do not actually pass through the image
_R____ Can be larger, smaller, or the same size as the object
Plane, Concave, or Convex Mirrors
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
concave_____ Form real or virtual images
plane, convex_____ Form only virtual images
plane_____ Form images that are the same size only
convex_____ Form images that are always reduced
concave_____ Form images that are either smaller/same size/larger than the object
concave_____ Form images that are either real or virtual
plane, convex_____ Form images that are only virtual
plane, convex_____ Form images that are behind the mirror
concave_____ Form images that are either behind the mirror or on the same side as the object
plane_____ Form images that are always the same distance from the mirror as the object
plane_____ Form images that have left to right reversal
plane, convex_____ Form images that are always upright
concave_____ Form images that are upright or inverted
plane_____ Are flat, smooth mirrors
concave, convex_____ Are curved mirrors
Ray Diagrams:
Image Characteristics: LOST
The goal of drawing Ray diagrams is to find the following:
L: _location
O: _orientation (upright or inverted)
S: _size (same, enlarged, reduced)
T: _type (real, virtual)
Complete each Ray Diagram and complete the LOST image characteristics to be expected:
Plane Mirror – Draw each reflected ray according to the Law of Reflection. Extend the rays on the other side of
the mirror to indicate where the image will be located.
behind mirror, upright, same size, virtual
Concave Mirrors – 5 cases
Convex Mirror
Behind mirror, upright, smaller, virtual
Concave mirror summary:
Case #
Object Location
Image location
Orientation
Size
Type
1
Beyond C
Between C & F
Inverted
Smaller
Real
2
At C
At c
Inverted
Same size
Real
3
Between C and F
Behind C
Inverted
Larger
Real
4
At F
No image
Na
Na
Na
5
In front of F
Behind mirror
Upright
Larger
virtual
Mirror Math
Mag = - di/do
1.
Determine the image distance and image height for a 5.00-cm tall object placed 30.0 cm from a concave
mirror having a focal length of 15.0 cm.
a. What is the magnification? –di/do -30/30 = -1
b. What case is this?
Answer: di = 30.0 cm and hi = -5.0 cm
1/15 = 1/30 + 1/di to solve for di then,
hi = -30
5 30
NOTE: this is "Case 2" because the image is inverted, real, same size as object
2.
Determine the image distance and image height for a 5.00-cm tall object placed 20.0 cm from a concave
mirror having a focal length of 15.0 cm.
a. What is the magnification? –di/do -60/20 = -3
b. What case is this?
Answer: di = 60.0 cm and hi = -15.0 cm
1/15 = 1/20 + 1/di to solve for di then,
hi = - 60
5 20
NOTE: this is "Case 3" because the image is inverted, real and larger
3.
Determine the image distance and image height for a 5.00-cm tall object placed 10.0 cm from a concave
mirror having a focal length of 15.0 cm.
a. What is the magnification? –di/do = 30/10 = 3
b. What case is this?
Answer: di = -30.0 cm and hi = +15.0 cm
1/15 = 1/10 + 1/di to solve for di then,
hi = 30
5 10
NOTE: this is "Case 5" because the image is upright, virtual and larger
Sign Conventions
f is NEGATIVE = if mirror is convex____________
di is NEGATIVE = if image is virtual_____________
hi is NEGATIVE = if image is inverted_____________