Understanding Light Travel: A Ks2 Guide

In this lesson, we will be learning about light, including what it is and where it comes from. We will also explore how light travels and how it interacts with different objects. To understand these concepts, we will conduct investigations using various materials such as light sources, paper, cardboard, and transparent objects. By observing how light behaves when it encounters transparent, translucent, and opaque objects, we can gain insights into the fascinating world of light and its properties. Additionally, we will delve into the topic of reflection and learn about reflective and non-reflective materials, as well as specular and diffuse reflection. Understanding how light travels and changes direction when reflected off surfaces will be key to unlocking the mysteries of light and its essential role in our lives.

Light travels in straight lines

The main reason light travels in straight lines is that it is a wave and always takes the shortest path between two points. This behaviour can be observed in everyday situations and is the reason why we see sharp-edged shadows. For instance, when light passes through a small hole, it spreads out, but each part of the beam still travels in a straight line from the hole.

However, it is important to note that light never travels in an exact straight line. There are several effects that cause light to deviate from a perfectly straight path, and these effects are known as diffraction and spacetime curvature. Diffraction causes the beam of light to spread out, with different parts of the beam bending in different directions, resulting in a curved path. This phenomenon is often observed in high-quality photographs of stars, where spikes of light appear attached to the stars.

Despite these deviations, light can be approximated to travel in straight lines in everyday situations, especially when travelling short distances through uniform air. This approximation is useful and applicable in many contexts, such as when teaching the basics of light behaviour to students.

Light travels out from its source in all directions

Light travels in straight lines out from its source in all directions. This means that light spreads out from a light source, such as a lamp or the sun, in a straight line. This is a fundamental property of light and is key to understanding how we see objects and how light can be reflected.

When light rays hit an object, they are either absorbed or reflected. Opaque objects, such as a table or a book, will absorb the light, which is why they appear solid and we cannot see through them. Transparent objects, like glass or water, will allow some light to pass through them, while other materials may only let a small amount of light through, like coloured paper or tinted windows.

Light can be reflected using mirrors. A mirror reflects light in a way that preserves much of its original direction, allowing us to see a clear image of objects. This is why we use mirrors for personal grooming or driving cars; they provide an accurate representation of the world around us.

Understanding how light travels and interacts with different materials is essential for KS2 students as it forms the basis of our perception of the world. It also has practical applications, such as in the design of optical instruments like microscopes and telescopes, which rely on the reflection and refraction of light to function.

Light and shadows

Light is essential for us to see things. Without it, we are in the dark, literally! Light travels in straight lines and can be reflected using mirrors. It is also interesting to note that white light is made up of a spectrum of colours.

Shadows are formed when light from a source is blocked by an opaque object. The opaque object prevents the light from reaching the surface behind it, creating a dark area in the shape of the object. The closer an object is to the source of light, the bigger the shadow it will cast.

Investigating Shadows

You can investigate the effects of light and shadows by creating a shadow puppet theatre. Using a bright torch as your light source, shine the light on a variety of objects to observe the shadows they cast. You can also experiment with moving the light source closer to or further from the objects to see how this changes the size of the shadows.

Light and Reflections

Light is reflected from surfaces, such as mirrors. Reflections can be used to navigate, such as seeing around corners with two mirrors. Light can also be reflected from other objects, like a torch reflecting off a shiny surface.

Protecting Our Eyes

It is important to remember that light from the sun is very powerful and can be dangerous to our eyes. We must never look directly at the sun, even with sunglasses on, as it can damage our eyes.

Light reflection and mirrors

Light travels in straight lines and can be reflected using mirrors. This is what we're going to explore in this lesson about light reflection and mirrors.

How Light Reflects

Reflections occur when light bounces off things. When light hits a reflective material, it bounces off, changing direction. This is called reflection. Light can reflect off nearly all materials, but some are better reflectors than others.

Smooth Surfaces

Smooth, shiny objects with flat surfaces, like mirrors, are the best reflectors of light. That's because mirrors are super smooth.

Changing Direction

Mirrors can be used to change the direction of light. This is how periscopes in submarines work. You can also use reflective materials to make light travel around an obstacle.

Experiment Ideas

There are lots of experiment ideas you can try to help you understand how light travels and how it can be reflected using mirrors.

Light refraction

You might have noticed this effect if you've ever looked at a straw sitting in a glass of water. The straw appears bent or broken at the water's surface. This is because the light from the straw is refracted as it passes from the air into the water, causing the image of the straw to change.

Another example of light refraction is when you shine a beam of light through a glass prism. The light is split into its different colours, creating a rainbow effect on nearby surfaces. This happens because the light is refracted by the glass at different angles, depending on its colour.

Frequently asked questions