Put the magnifying glass between the wall and the window About 10-30 cm (4 -12 inches). You will see the right distance will be in focus on the wall.
Most magnifying glasses are double-convex lenses and are used to make objects appear larger. This is accomplished by placing the lens close to the object to be viewed. In this way the light rays are bent toward the center of the lens. When these bent rays reach the eye they make the object appear much larger than it actually is. However, if the object is far enough away from the lens, the image will flip, appearing smaller and upside down. The distance at which this flip occurs is twice the focal length (the distance from the optical center of a lens to the point where the light rays converge) of the lens. The focal length of any lens is determined by the amount of curve on the lens’ face. The magnified image is called a virtual image while the smaller, inverted image is called the real image.
We know magnifying glass can start a fire, so don’t do this experiment in direct sun light, as it will get hot and is not good on the paint.
If you get the magnifying glass the right distance from the wall you should see an upside down image of what is outside projected on the wall.
You will find that if you move the magnifying glass too close or too far away from the wall the image will go all fuzzy.
The magnify glass is a lens. This is a specially shaped piece of glass that has an interesting property. All the light coming from one spot on one side of the lens is bent so that it is concentrated (focused) through a single point on the other side.
A digital camera works on the same principle but instead of a piece of film it has a CCD, an electronic sensor which is read by a small computer in the camera.