# Solution to Optics Lens Problem: Image Distance in f

• Gshan12
In summary, the conversation is about finding the image distance in terms of f when a real object is located to the left of a convergent lens with a focal length of f and a distance of 7/3f. The formula 1/f = 1/di + 1/do was tried but did not work, leading to confusion and errors. After discussing and correcting a mistake, the solution was successfully found.
Gshan12
i need help!

Given: A real object is located to the left of a convergent lens. The object's distance from the lens is 7/3f and its focal length is f. What is the image distance in terms of f?

I tried the formula 1/f = 1/di + 1/do... it didn't work

Gshan12 said:
I tried the formula 1/f = 1/di + 1/do... it didn't work
What makes you think that doesn't work?

i got a weird fraction that di= (1-3f^2)/(f^2) and it's not one of the answer choices.

I don't see how you get $f^2$. Redo it, carefully: $o = 7f/3$, so $1/o = 3/(7f)$. $1/i = 1/f - 3/(7f)$, etc.

oh! i made a stupid math mistake...

THANK YOU SO MUCH!

## What is the formula for calculating image distance in f?

The formula for calculating image distance in f is di = f1do/(f1 + do), where di is the image distance, f1 is the focal length of the lens, and do is the object distance.

## What do the variables in the image distance formula represent?

The variable di represents the distance from the lens to the image, f1 represents the focal length of the lens, and do represents the distance from the lens to the object.

## How does changing the object distance affect the image distance?

Changing the object distance directly affects the image distance, as shown in the formula. As the object distance increases, the image distance also increases. Similarly, as the object distance decreases, the image distance also decreases.

## What is the difference between a real image and a virtual image?

A real image is formed when light rays actually converge at a point and can be projected onto a screen. It is always inverted and can be seen on a screen or surface. On the other hand, a virtual image is formed when light rays only appear to converge at a point, and it cannot be projected onto a screen. It is always upright and can only be seen when looking through the lens.

## How does the focal length of a lens affect the image distance?

The focal length of a lens directly affects the image distance. As the focal length increases, the image distance also increases. Similarly, as the focal length decreases, the image distance also decreases. This is because the focal length determines the strength of the lens and how much it can bend light rays.

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