Постройте изображение предмета, находящегося между фокусом и двойным фокусом собирающей линзы. Какое это изображение?

Unclear question. Here's the clear rendering of the text;

"Build an image of the subject between the focus and the double focus of the collecting lens. What is this image?".

Explanation:

Based on the information above you are to conduct an experiment using a lens to view the image provided.

Also based on the type of image, there are two types of lenses you can use:

Thus, by doubling the focus of the lens you should be able to identify the shape the image.

r=rho l/a where a is the area, l is the length and rho is resistivity so the greater the area the lesser the resistance thats why the earth pin is thicker bcos current follow the shortest path, so less resistive .

that tool is called an altimeter which measures your altitude which can be used to tell which atmosphere you are currently in, including the stratosphere.

hope this ! : )