Thin-Lens Ray Tracing, Image Formation, and Aberration

All flashcards

What is a converging lens?

A lens that refracts rays toward its optical axis; parallel incoming rays meet at a real focal point on the far side.

What is a diverging lens?

A lens that refracts rays away from its optical axis; its outgoing parallel-ray bundle appears to originate at a virtual focal point on the incoming side.

Define focal length.

The distance from the center of a lens to its focal point, denoted by $f$.

When is a lens considered thin?

When its thickness is much smaller than the radii of curvature of both surfaces, allowing the bending to be approximated at the lens center.

What does reversibility of light imply for a converging lens?

Rays directed from the focal point through the lens emerge parallel to the optical axis, reversing the usual parallel-ray-to-focus path.

Quiz questions

1. Which equation relates object distance $d_o$, image distance $d_i$, and focal length $f$ for a thin lens?Answer: $\frac{1}{d_o}+\frac{1}{d_i}=\frac{1}{f}$
2. According to the thin-lens lens maker’s equation, what determines a lens’s focal length?Answer: Refractive-index contrast and the curvature of both surfaces
3. For a thin lens, what does positive magnification indicate about the image?Answer: The image is upright relative to the object.
4. What image does a diverging lens form from a real object?Answer: A virtual, upright, reduced image on the object side
5. What causes chromatic aberration in a lens?Answer: Different wavelengths experience different refractive indices and focal lengths.