Find Object Position for Upright and 4x Sized Image | Concave Mirror Formula

In summary, the conversation is about determining the object position for a concave mirror with a focal length of 62.4 cm, where the resulting image is upright and four times the size of the object. The formula used for this question is h'/h = -q/p and 1/p + 1/q = 1/f. The person is struggling to find the answer and is advised to draw a ray diagram and pay attention to the sign conventions for the concave mirror. They eventually realize that the linear magnification is positive and use the definition of m to write the object distance in terms of the image distance. Finally, they use the mirror equation to solve for the object distance and determine the answer.
  • #1
Aerospace
39
0
Stumped...lol..

A concave mirror has a focal length of 62.4 cm.
Determine the object position for which the resulting image is upright and four times the size of the object.

What formula do I use for this question? :confused:
 
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  • #2
h'/h = -q/p
1/p + 1/q = 1/f
 
  • #3
haha...i already knew those formulas.
but what's stumping me is...i only know f and the magnitude -.-
is there something that I'm not seeing? i can be totally blind sometimes!
 
  • #4
I don't understand. What is "-.-"? Try drawing a ray diagram to help you visualize. Beware of the sign conventions for the concave mirror (which I don't recall off the top of my head).
 
  • #5
What is the answer meant to be?
 
  • #6
Aerospace said:
haha...i already knew those formulas.
but what's stumping me is...i only know f and the magnitude -.-
is there something that I'm not seeing? i can be totally blind sometimes!
You have all the info needed to solve this problem, you're just not putting things together. The fact that the image is upright means that the linear magnification is positive: in this case m = +4. Now use the definition of m to write the object distance (p) in terms of the image distance (q). Then when you plug into the mirror equation, you can solve for p.
 
  • #7
yup because
m = distance of image/distance of object so we can say that m = 4 hence
di = 4 x do (where i and o represent image and object)

Then we can plug that into the equation for focal length which is
1/di + 1/do = 1/f
and we know the f, so we can solve for 'do' to get the answer :)

thanks very much.
 

1. What are lenses and mirrors?

Lenses and mirrors are optical devices that are used to manipulate light. Lenses are transparent objects made of glass or plastic that can bend light rays, while mirrors are smooth, reflective surfaces that can reflect light.

2. What is the difference between a convex and concave lens?

A convex lens is thicker in the middle and thinner at the edges, causing light to converge and focus at a point. A concave lens is thinner in the middle and thicker at the edges, causing light to diverge.

3. How do mirrors reflect light?

Mirrors reflect light through a process called specular reflection, where light rays bounce off the smooth surface at the same angle that they hit the surface.

4. What is the difference between a plane mirror and a curved mirror?

A plane mirror has a flat, smooth surface that reflects light in a predictable way, while a curved mirror has a curved surface that can cause light to converge or diverge depending on its shape.

5. How are lenses and mirrors used in everyday life?

Lenses and mirrors are used in a variety of everyday objects, such as eyeglasses, cameras, and telescopes. They are also used in scientific instruments, like microscopes and telescopes, to manipulate and magnify light for research and observation.

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