Ray Diagrams and Light Transmission - Year 7 PDF Download

Introduction

• Light behaves as a transverse wave, where particles move perpendicularly as it travels, akin to the motion of an ocean wave or a rope being lifted. It progresses in straight lines.
• Transparent and translucent materials allow light to pass through for clear visibility, while opaque substances block light entirely.
• Ray diagrams utilize straight lines to depict light rays, with arrows indicating their directional movement.

Opaque, translucent and transparent materials

• Light travels as waves. These are transverse waves where particles move up and down at right angles to the direction of travel, similar to ripples in water.
• The vibration direction in light waves is perpendicular (90 degrees) to the direction of light travel.
• Light waves can travel through a vacuum, which is empty space devoid of solid, liquid, or gas.

Transparent Materials

• Materials that allow light to pass through them, enabling clear visibility of objects.
• Examples include water and glass.
• When light passes through transparent materials, objects can be clearly seen.
• Illustration: Clear glass windows in a building allow people to see outside clearly.

Translucent Materials

• Substances that permit some light to pass through but not as clearly as transparent materials.
• An example is frosted glass on a shower door.
• Images viewed through translucent materials may appear distorted as light partially passes through.
• Explanation: Frosted glass in a bathroom allows light to enter but blurs the view for privacy.

Translucent Objects

• Translucent objects allow some light to pass through, but they scatter it in different directions.
• Examples of translucent objects include ice, thin fabrics, and greaseproof paper.
• When light passes through translucent objects, it becomes diffused and the objects appear somewhat see-through.

Frosted glass is translucent. It allows some light to pass through, but images of objects viewed through the frosted glass are not clear.

Opaque Materials

• Opaque materials do not allow light to pass through them; examples include stone, metal, and wood.
• Light is absorbed, scattered, or reflected by opaque materials, preventing it from passing through.
• When light hits opaque materials, it is either absorbed, scattered in various directions, or reflected back.

Transmission of Light through Different Materials

Light transmission varies depending on the material it passes through. Opaque materials block light completely, allowing no light to pass through. Translucent materials allow some light to pass through, but it is diffused or scattered. Transparent materials, on the other hand, allow light to pass through without scattering, allowing all light to transmit through them clearly.

How Light Travels to Your Eye

Luminous Objects

• Luminous objects, such as the Sun, are visible because they emit their own light, which travels directly from the source to the eye.

Non-Luminous Objects

• Non-luminous objects, like the Moon, are visible as they reflect light from luminous sources. The light follows a straight path from the object to the eye.
• Ray diagrams are utilized to illustrate the path of light, representing light rays as straight lines with arrowheads indicating the direction of travel.

This diagram shows the difference between the path of light travelling from a luminous and a non-luminous object.