Image distance

Definition

Image distance is the distance between the image formed by a lens and the lens itself. It is usually denoted by $d_i$ and can be positive or negative depending on the type of image formed.

5 Must Know Facts For Your Next Test

1. The sign of the image distance ($d_i$) indicates whether the image is real (positive $d_i$) or virtual (negative $d_i$).
2. Image distance can be calculated using the lens equation: $\frac{1}{f} = \frac{1}{d_o} + \frac{1}{d_i}$, where $f$ is the focal length and $d_o$ is the object distance.
3. In a converging lens, a real image forms on the opposite side of the object, making $d_i$ positive.
4. In a diverging lens, a virtual image forms on the same side as the object, making $d_i$ negative.
5. The magnification of an image can be found using $\text{Magnification} = -\frac{d_i}{d_o}$.

Review Questions

• How do you determine if an image is real or virtual based on its image distance?
• What does a positive value for image distance signify in terms of image formation?
• How would you use the lens equation to solve for an unknown image distance?

Related terms

Object Distance: The distance between an object and a lens, usually denoted by $d_o$. It influences where and how an image will form.

Focal Length:

The distance from the center of a lens to its focal point. It determines how strongly the lens converges or diverges light.

Magnification:

$\text{Magnification} = \frac{\text{Image Height}}{\text{Object Height}} = -\frac{d_i}{d_o}$. It describes how much larger or smaller an image is compared to its object.