A 3cm tall object is placed 40cm from a concave mirror with a focal distance of 16cm. The object is moved to 10cm from the same mirror. How would you calculate the distance to the image from the lens, the magnification, and the height of the image?

1 Answer
Apr 21, 2017

d_i=-80/3cm

m=8/3

h_i=8cm

Explanation:

I assume that "lens" should be "mirror."

We can use the mirror equation to find the image distance:

1/f=1/d_i+1/d_o

Where f is the focal length, d_i is the distance from the mirror to the image, and d_o is the distance from the mirror to the object.

We can then use our values for d_i and d_o to calculate the magnification, which is given by the equation:

m=(-d_i)/(d_o)

And using the fact that

m=(-d_i)/(d_o)=h_i/h_o

we can solve for h_i and use the value we obtain for m as well as h_o to calculate:

h_i=m*h_o

We are given that:

h_o=3cm

f=16cm

d_o=10cm

1. Calculate d_i:

1/f=1/d_i+1/d_o

=>1/d_i=1/f-1/d_o

=>d_i=(1/f-1/d_o)^-1

=(1/16-1/10)^-1

=-80/3cm

~~ -26.7cm

2. Calculate m:

m=-d_i/d_o

=-((-80/3))/10

=80/30

=8/3

3. Calculate h_i:

m=h_i/h_o

=>h_i=m*h_o

=(8/3)(3)

=8cm