# Distance between the object and the lens

Libra_girl

## Homework Statement

A diverging lens of 6 mm focal length produces an image of magnification m = 1/2. What
is the distance between the object and the lens?

Homework Helper
Welcome to PF!

## Homework Statement

A diverging lens of 6 mm focal length produces an image of magnification m = 1/2. What
is the distance between the object and the lens?

Hi Libra_girl ! Welcome to PF!

Hint: what equations do you know that relate the size of the object to the size of the image?

Libra_girl
Hi Libra_girl ! Welcome to PF!

Hint: what equations do you know that relate the size of the object to the size of the image?

Is it the equation: do/di = m or 1/do + 1/di = 1/f ?

Homework Helper
Is it the equation: do/di = m or 1/do + 1/di = 1/f ?

Both equations!

Except isn't it m = -di/do?

Libra_girl
Both equations!

Except isn't it m = -di/do?

yeah it is sorry

Last edited:
Libra_girl
yeah it is sorry

Both equations!

Except isn't it m = -di/do?

Ok so I know f and I know m, now I am solving for do, but I don't know the di?

Homework Helper
Hi Libra girl,

You now have two equations in two unknowns. You can solve the magnification formula for one of the variables and plug it into the other formula. What does that give?