🦋 Lenses and the images they produce.

Cameras, telescopes, microscopes, and magnifying glasses produce images.

The images produced by telescopes, microscopes and magnifying glasses are bigger than the object looked at.

The image produced and captured by cameras is smaller than the object.

Of all the instruments  mentioned magnifying  glasses is the one where most of us have used.

Lenses can be divided into 2  categories  depending on the shape of their surfaces - Convex lens and concave lens. (For this post, we shall ignore that are flat on one side and convex/concave on the other side)

Lenses  have focal length. Where we place on object compared to the focal length will have effects on the image it produce : the position of the image, whether the image is real or virtual, whether the image is upright or inverted (upside down), and whether the image is magnified/diminished (size of the image)

Those who are studying physics may be asked about the quality of images as mentioned in the above paragraph.

They may also be asked to draw ray diagrams for different types of lenses  based on the position of the object compared to the focal length of the lens.

The video below explains the concepts more clearly than textbooks do. It even tell you tips how you can cheat to ensure your ray diagram is correct.

If you know the theory, do not draw rays and take the point where the rays meet to produce the image. Inaccuracies in your drawing may produce wrong answers.

Draw the image at the correct position and of the right size. Then draw the rays to fit the image.

Question 1

How does how far away we place the magnifying glass from an object have an effect on the size of the image we see?

Question 2

Why can we use a magnifying glass to light a fire?

Question 3

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