Question

An object is placed 7.0 cm away from a converging lens with a focal length of 7.0cm

you will use the lens equation to solve the problem

Answer 1

x
=
7

c
m
is the object distance
f
=
5

c
m
is the lens focal length
To solve where the image is located, we use the thin lens equation:

1
f
=
1
x
+
1
y

and we isolate the image distance:

1
y
=
1
f
−
1
x

we substitute:

1
y
=
1
5

c
m
−
1
7

cm

1
y
=
0.2cm
−
0.14286cm

1
y
=
0.057143cm

we obtain the image location:

y
=
17.5cm