CBSE Class 7 Science Chapter 11 Light Shadows and Reflections Notes 2025-26

Light is a form of energy that enables us to see things around us. We observe light from both natural and artificial sources in our daily life. The Sun is the primary natural source of light and is supported by other sources like stars, lightning, natural fire, and some animals such as fireflies. These sources emit their own light, and such objects are called luminous objects.

Objects like the Moon, mirrors, and paper do not produce their own light; rather, they reflect light from luminous sources. These are known as non-luminous objects. For example, the Moon appears bright in the night sky because it reflects sunlight.

In earlier times, humans discovered fire and used different materials such as animal fat, oil, wax, and gas for lighting. Today, we use many artificial sources of light like electric bulbs, tube lights, LED lamps, and other devices. Modern LED lamps are especially popular because they use less electricity, provide bright light, last longer, and are more eco-friendly. It is important to recycle or dispose them correctly after use.

A key feature of light is that it generally travels in a straight line. You can test this by aligning three matchboxes with holes in the trays, shining a torch through them. If even one hole is out of line, the light no longer passes through. Similarly, looking through a straight pipe at a candle allows you to see the flame, but if the pipe is bent, the flame cannot be seen. These experiments show that the path of light is a straight line.

Materials can be classified into three groups based on how they interact with light: transparent, translucent, and opaque.

• Transparent materials (like clear glass) let almost all light pass through them easily.
• Translucent materials (like tracing paper) allow light to pass through partially, making objects look blurred.
• Opaque materials (like cardboard) do not let light pass through at all, blocking it completely.

If you shine a torch on a screen and place different materials in front, you will notice these differences in how much light reaches the screen. Sometimes, under special conditions, light can bend around corners, but that is mostly studied in higher classes.

A shadow is formed when an opaque object blocks the path of light. The region where light does not reach becomes dark and is called a shadow. To observe a shadow, three things are needed: a source of light, an opaque object, and a screen. The properties of the shadow—its size, shape, and sharpness—depend on the positions of the light source, the object, and the screen. Opaque objects form well-defined, dark shadows, while translucent objects create lighter ones, and transparent materials may give a faint shadow.

The color of an object usually does not affect the color of the shadow, but different colors on the light source (such as using colored transparent paper over a torch) may make the shadow appear tinted. The size of the shadow increases when the object moves closer to the light and decreases when it is closer to the screen. Removing the screen, object, or turning off the torch means the shadow disappears.

Reflection is the process by which light bounces off a shiny surface like a mirror or a smooth steel plate. When you direct sunlight or a torch at a plane mirror, the reflected light can be seen on a different surface. The direction of the reflected beam changes based on the angle of the mirror. Reflection is the reason we see our image in mirrors.

The image you see in a plane mirror has several important properties:

• It is the same size as the real object.
• The image is erect (upright).
• The image appears behind the mirror, at the same distance as the object is in front of it.
• It cannot be obtained on a screen.
• It is laterally inverted (left appears right and right appears left).

If you write your name on a paper and hold it in front of a mirror, the letters will appear reversed sideways. This effect is called lateral inversion.

A pinhole camera is a simple device made using a box with a tiny hole on one side and a screen on the other. Light from an object passes through the hole and forms an image on the screen inside the box. The image formed by a pinhole camera is inverted (upside down). Activities with candles and cardboard can help demonstrate the working of this camera.

A periscope uses two plane mirrors set at an angle inside a box to let you see objects that are not in your direct line of sight. Periscopes are used in submarines and bunkers to look at objects above obstacles.

A kaleidoscope is made using three plane mirrors joined in a triangular tube, with colored pieces at one end. Looking through the tube, you see beautiful, ever-changing patterns due to multiple reflections. Designers often use kaleidoscopes to get ideas for new patterns.

• Luminous objects give out their own light, while non-luminous objects reflect light.
• Light usually travels in a straight line.
• Transparent, translucent, and opaque materials allow light to pass through them to different extents.
• Shadows are formed when light is blocked by opaque objects, depending on their position.
• Reflection of light from mirrors enables us to see images; these images are equal in size and laterally inverted.
• A pinhole camera produces an inverted image of an object on a screen.
• Devices like periscopes and kaleidoscopes use the principles of reflection to perform interesting functions.

Class 7 Science Chapter 11 Notes – Light Shadows and Reflections: Key Points for Quick Revision

These comprehensive Class 7 Science Light Shadows and Reflections notes make it easy to quickly revise all main topics like sources of light, shadows, and reflection. Short, simple definitions and key points help students grasp important concepts. Perfect for last-minute exam revision or homework understanding.

Get a clear summary of Light: Shadows and Reflections with helpful tables, examples, and bullet points. Focused notes structure enables easy learning of differences between transparent, translucent, and opaque materials, as well as key ideas about images, shadows, and pinhole cameras.