# Why are virtual images created

## Understand physics 4, textbook

17 The world of the visible  Learning objective check 4, page 85 3. How does a magnifying glass work? A magnifying glass (Fig. 17.1) Observe a candle flame through a converging lens so that you can see its image enlarged and upright. Can you also capture the picture of the candle on a screen? When trying to capture the light from the candle at V4, you will have noticed that the light spot diverges further and further and does not create a light image. The image you see in the magnifying glass is apparent (virtual). In Fig. 17.2 you can see how the virtual image of the magnifying glass is created. M A converging lens acts as a magnifying glass when the object is within the focal length. The image is apparent (virtual), upright and enlarged. 4. How are images created on diverging lenses? Diverging lenses are thinner in the middle than at the edge. They are also called concave lenses (lat. Concavus = hollowed out). Reduced images (Fig. 17.4) Look at a candle through a diverging lens. Change the distance and try to catch a light image with a screen. If you let parallel rays of light fall through a diverging lens, they diverge after the lens as if they came from a divergence point Z (Fig. 17.3). As a result, the light rays no longer meet after the lens and cannot generate a real light image. All images on the diverging lens are therefore virtual. Here, too, the special rays can help us to understand the creation of the image: Parallel rays run after the lens as if they came from the point of diffusion Z 1. Rays in the direction of the divergence point Z 2 run parallel after the lens. Center rays are not deflected. M Only apparent (virtual), reduced and upright images can be seen through diverging lenses. V4 V5 17.1 A magnifying glass 17.2 This is how a virtual image is created on the converging lens. F 2 a virtual image F 1 17.4 Reduced images a virtual image Z 1 Z 2 17.5 This is how the virtual images are created on the diverging lens. 17.6 An empty glass ball acts like a concave lens in water. 17.3 The beam path on the diverging lens Z For testing purposes only - property of the publisher öbv