Why shadows change length during the day

Now move the lamp over the object. How does the shadow change? A shadow happens when an object blocks the path of light. The object must be translucent or opaque. Opaque objects make darker shadows; translucent objects make lighter shadows. The closer an object is to the light source, the larger the shadow will be. At noon, the Sun is overhead and objects cast short shadows or no shadow at all. The length of shadows changes as Earth rotates.

In the morning, the sun is low in the eastern sky and shadows are long. At the time of sunrise if a man stands facing the east, his shadow will be towards west.

At the time of sunset the shadow of an object is always in the east. If a man stands facing the North, at the time of sunrise his shadow will be towards his left and at the time of sunset it will be towards his right. East is in the clockwise direction of rotation from north. West is directly opposite east. In the morning, the sun rises roughly in the east and tracks upwards.

Answer: Shadows are longer in the morning and evening and short in the noon because the sun rays are slanting in the morning and evening whereas at noon it is just above our head.

The size of the shadow depends on the position of the object from the source of light. Look at the illustration to the right and notice the direction of the shadow is away from the source. During midday it would be the shortest, and in afternoon it would be on the opposite side. If the sun is low in the sky 10 degrees , your shadow would be 5. The corresponding ratio at 5 degrees is So an average height person 5.

At noon the sun is directly overhead, the sun rays fall vertically on the body so the shadow is very short. In the morning or in the evenings, the sun rays fall in an inclined position,so the shadows are long. Noon is going to produce the shortest shadow of the day, though this length will vary based on the time of year and how far north or south of the equator you are.

Shadows grow bigger and fuzzier as the object moves closer to the light source, and smaller and sharper as the object moves farther away.

Shadows are important historically, for they provided early evidence that light travels in straight lines. The closer an object is to the light source, the larger the shadow it casts. This is because an object closer to the source will block a larger area of the light, increasing its shadow size. A shape of an object always determines the shape of its shadow. However, the size and shape of the shadow can change.

These changes are caused by the position of the light source. Simply speaking, a shadow is an absence of light. If light cannot get through an object, the surface on the other side of that object for example, the ground or a wall will have less light reaching it. There are many sources of light — stars like our Sun, candle flames, light bulbs, glow-worms and computer screens produce light. All of this light travels in a straight line until it hits something.

Sometimes, it travels a short distance — like when we switch on the lamp. Other times, light travels thousands of years — like the light from stars we see in the Milky Way. It is easy to see our shadows when we are outdoors in the sunshine on a clear, bright sunny day, but do shadows form when an object blocks light from other sources?

The answer is yes, but they may be difficult to see if the light source is not very bright has a low light intensity. Shadows are also more definite sharper where there is contrast between the shadow and the lit surface, for example, a shadow on a white wall will be more easily seen. The size of the light source can sharpen or blur the shadow.

A small spotlight like a cellphone torch forms a more distinct shadow than an overhead room light, but the sharpness of the shadow changes when the torch moves away from the object. A shape of an object always determines the shape of its shadow. However, the size and shape of the shadow can change. These changes are caused by the position of the light source. When we are outside on a sunny day, we can see how our shadows change throughout the day. When the Sun is low on the horizon, the shadows are long.

When the Sun is high in the sky, the shadows are much shorter. We can create the same effects indoors by changing the position of a torch as it shines on an object.

Although the shadow effects are the same, the reasons for the moving light source are very different. When we use a torch to make long and short shadows indoors, it is the light source that moves.