Chapter 30, Problem 43A

Make a pinhole camera, as illustrated in the figure. Cut out one end of a small cardboard box,- and cover the end with tissue paper. Make a clean-cut pinhole at the other end. Aim the camera at a bright Object in a darkened room, and you will see an upside-down image on the translucent tissue paper. In a dark, windowless room, if you replace the tissue paper with unexposed photographic film, cover the back so it is light-tight, and cover the pinhole with a removable flap, you will be ready to take a picture.

Exposure times differ, depending mostly on the kind of film and the amount of light. Try different exposure times, starting with about 3 seconds. Also try boxes of various lengths. You'll find everything in focus in your photographs, but the pictures will not have clear-cut, sharp outlines. The principal difference between your pinhole camera and a commercial one is the glass lens, which is larger than the pinhole and there-fore admits more light in less time.

To determine

To explain why does the body make a substance that can potentially damage the circulatory system which is nothing but cholesterol that usually associated with negative effects on our circulatory system.

Explanation of Solution

Introduction:

Cholesterol plays a very important role in our body. It acts as the structural component of the cell. It is the energy source of the cell. It works as important signalizing molecule.

When a person takes excess food then the lipids store the energy in the form of fat for later use, which requires for the metabolic activities. The level of cholesterol for a healthy man is $125\text{ to }200\text{ mg}/\text{dL}$ . This level exceeds when you take saturated fats in your diet. If the level of cholesterol increases then the fat content in our body exceeds beyond limit. Then this fat deposites on our blood vessels and choke it, which restricts the flow of blood and finally attacks to heart.

Conclusion: Due to its huge importance body makes it in itself.