Question

REMARKS The negative value of q indicates the image is virtual, or behind the mirror. The image is upright because M is positive.

QUESTION Is the image that a convex mirror produces real or virtual?

The image is always real.It depends on the focal length of the mirror.    The image is always virtual.It depends on the distance to the object.

PRACTICE IT

Use the worked example above to help you solve this problem. An object 3.13 cm high is placed 20.1 cm from a convex mirror with a focal length of 7.70 cm.

(a) Find the position of the image.
cm

(b) Find the magnification of the mirror.


(c) Find the height of the image.
cm

EXERCISEHINTS:  GETTING STARTED  |  I'M STUCK!

Suppose the object is moved so it is 3.85 cm from the same mirror. Repeat parts (a) through (c).

(a) q =  cm

(b) M =

(c) h' =  cm

The image is  ---Select--- upright and virtual inverted and virtual inverted and real upright and real .

Answer 1

The image is always virtual.

Reason : Image formed by convex mirror is always virtual.

f = focal length of convex mirror = - 7.70 cm

d_o = object distance = 20.1 cm

d_i = image distance = ?

h_o = object height = 3.13 cm

a)

Using the mirror equation

1/d_o + 1/d_i = 1/f

1/20.1 + 1/d_i = 1/(- 7.70)

d_i = - 5.6 cm

5.6 cm on the other side of mirror.

b)

magnification is given as

m = - d_i /d_o = - (- 5.6)/20.1

m = 0.28

c)

magnification is also given as

m = h_i/h_o

0.28 = h_i/3.13

h_i = 0.88 cm

f = focal length of convex mirror = - 7.70 cm

d_o = object distance = 3.85 cm

d_i = image distance = ?

h_o = object height = 3.13 cm

a)

Using the mirror equation

1/d_o + 1/d_i = 1/f

1/3.85 + 1/d_i = 1/(- 7.70)

d_i = - 2.6 cm

2.6 cm on the other side of mirror.

b)

magnification is given as

m = - d_i /d_o = - (- 2.6)/3.85

m = 0.68

c)

magnification is also given as

m = h_i/h_o

0.68 = h_i/3.13

h_i = 2.13 cm

The image is upright and virtual