Dioptre

High school (ages 12+)
Human Body

Name:

Date:

Step 1 · Read the article

Open the article and read it at the level above. Then answer the questions below in your own words.

https://smallwhale.org/articles/dioptre

Write what each word means, using the article.

Do not copy the article. Write two things you learned, the way you would explain them to a friend.

Answers below are taken from the article’s stored facts, so they match what the student read.

1. What is the definition of optical power?The reciprocal of the focal length expressed in meters (P = 1/f)
2. What is the dimensionality?The dioptre has dimensions of inverse length (m⁻¹)
3. How do we use dioptres to fix blurry vision?Doctors write a number in dioptres on an eyeglass prescription. A negative number means a lens that spreads light out (for nearsighted people) and a positive number means a lens that brings light together (for farsighted people).
4. Why do some lenses have positive and some have negative dioptres?A positive dioptre means the lens is convex and pulls light together, while a negative dioptre means the lens is concave and pushes light apart.

Reciprocal: A number that, when multiplied by another, equals one; the 'flip side' of a number.
Optical Power: A measure of a lens or mirror's ability to refract or reflect light.
Vergence: A measure of the curvature of a light wavefront, indicating how much light is converging or diverging.
Thin Lens Approximation: A simplification assuming lens thickness is negligible compared to focal length.