lens problems

[eku_girl83]

1) Aconverging lens with a focal length of 7 cm forms an image of a 4 mm tall real object that is to the left of the lens. The image 1.10 cm tall and erect.
Where is the object located?
Where is the image located?
2) A converging lens with a focal length of 12 cm forms a virtual image 5 mm tall, 19 cm to the right of the lens.
Determine the position of the object. (Give the object distance with the correct sign).
Determine the size of the object.

[Doc Al]

You'll need the lens equation: 1/f = 1/o + 1/i, and the definition of linear magnification: m = -i/o.

Look up how these equations are used and give the problems a try.

[gfak25]

1) Aconverging lens with a focal length of 7 cm forms an image of a 4 mm tall real object that is to the left of the lens. The image 1.10 cm tall and erect.
Where is the object located?
Where is the image located?
2) A converging lens with a focal length of 12 cm forms a virtual image 5 mm tall, 19 cm to the right of the lens.
Determine the position of the object. (Give the object distance with the correct sign).
Determine the size of the object.
There is a good simulation program picture what about it
http://www.geocities.com/mrfarag