Please help me!!

A mirror of focal length 26.6 cm creates an image with magnification −0.350. What is the image distance?

if know what the answer is... can you explain it to me. thnxs!!!

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- May 7th 2009, 04:53 PMsoojin89mirror equation...hate them!!
Please help me!!

A mirror of focal length 26.6 cm creates an image with magnification −0.350. What is the image distance?

if know what the answer is... can you explain it to me. thnxs!!! - May 9th 2009, 06:33 AMfardeen_gen
You haven't mentioned whether it is a concave or convex mirror. So I am taking cases.

Using the mirror equation,

where:

- object distance

- image distance

- focal length of the mirror

(NOTE: The equation is formulated defining the pole as origin and the quantities denote the x-coordinates)

(For concave mirror):**CASE I**

We have,

= - 26.6 cm (Considering focus towards left of pole as it is a concave mirror)

So using mirror equation,

--------- ■

We know that,

Magnification = =

(The equation is formulated taking proper signs)

Thus,

-------- ●

Using the above relation in ■,

(rejected as image cannot be formed at the pole)

or

Using ●,

Thus, the image is formed at a distance of towards the left of the concave mirror. (The negative sign implies negative x-axis which is towards the left of the origin i.e the pole)

Similarly,

(For Convex mirror):**CASE II**

We have,

= + 26.6 cm [Considering focus to the right of the pole]

Repeating the rest of the process,

Thus, the image is formed at a distance of towards the right of the convex mirror.

(The positive sign implies positive x-axis which is towards the right of the origin i.e. the pole)