An object is an identifiable grouping of matter restricted by a distinguishable boundary and can move as a unit by rotation or translation in a 3-D space. Each object has an exclusive independent identity.

Before explaining the difference between transparent, translucent, and opaque objects, let us first understand what the term object means.

## Types of Objects

We can see different kinds of objects around us, such as tube-light, pens, fans, computers, papers, stones, a chair and so on. All these objects possess independent properties. Objects are made of matter. For example, chairs are made of wood, and utensils are made of steel.

Objects are classified as luminous and non-luminous. Before we explain luminous and non-luminous objects, let us learn what visible and invisible objects are.

Objects that can be seen are visible, and objects that cannot be seen are called invisible objects.

## How are Objects Visible

One may wonder how we can see objects? When light passes through an object entering our eyes, then we can see the object. This light may either be reflected by an object or emitted by it.

## Luminous and Non-luminous Objects

Let us now explain luminous and non-luminous objects.

• Luminous Objects: If an object emits light, then the object is termed a luminous object. Examples:
• The Sun emits its light.
• Other examples of luminous objects are a torch, candles, stars, the filament of a bulb, fireflies, etc.
• Non-Luminous Objects: Objects that do not have their light are known as non-luminous objects. Examples:
• The moon reflects the light coming from the Sun.
• Earth and other planets, trees, and paper.

## Transparent Translucent and Opaque

Objects differ in how they emit light. All that we see around us appears different and has different properties. Some objects are transparent, some translucent, while some are opaque.

## What are Transparent Objects?

We use the word “transparent” as an adjective to describe an object “that is see-through or clear”. Transparent objects are those objects that enable light to pass or enter through them. Materials such as water, air, and also clear glass are transparent objects. When the light comes across transparent objects, almost all of the light passes through them directly.

Glass is an object that is transparent to light, air, and even water. For example, if we switch on a torch and point the torch at a glass window, the light can be seen on the other side of the glass window. This is possible as the light rays emitted from the torch pass through the glass window.

## What are Translucent Objects?

We use the word “translucent” as an adjective to define an object “enabling light to go or pass through it but at the same time not displaying clear images on the other side.”

Translucent objects are objects that fall between transparent and opaque materials. Translucent objects enable or allow some amount of light to pass through them, but only partially. Examples are frosted glass and some plastics.

When light strikes translucent materials, only some amount of light passes through the material. The light changes direction many times and is scattered as it passes through a translucent object. That is the reason we cannot see clearly through these objects. Also, the objects on the other side of a translucent object appear fuzzy and unclear.

For example, think of a fogged-up glass pane. If a person crosses a foggy glass window, one should guess that it is a person crossing the window; however, one may not be able to guess who or sometimes what is passing through as the details are not visible clearly. This is because translucent objects enable some light rays to pass through them but not all.

## What are Opaque Objects?

The word opaque is used as an adjective to describe an object “not capable of having light pass through.” Opaque objects block the light completely and do not allow any amount of light to pass through them. Most light that passes through opaque objects is either absorbed by the object or reflected completely and then transformed to thermal energy.

For example, stone, metals, and wood are opaque to visible light. Bricks, book covers, closed textbooks, and all other solid things are opaque by nature. Generally, some materials may be opaque to light but not to other types of waves that are electromagnetic.

## Difference Between Translucent and Transparent Objects

As explained already, transparent objects enable light to pass through them without being scattered, and translucent objects also enable light to pass through them; however, only partially. One can certainly see through transparent objects as they enable clear and proper image formation.

You must note that you can also see through translucent objects, but the image seen through translucent objects is not clear. Translucent objects do not enable clear image formation due to partial visibility. Thus, materials are displayed as stained and frosted. Transparent objects never form shadows as they cannot block light. Shadows are only formed by objects that block light. Translucent objects form faint shadows since they can block the light partially.

All transparent objects come under the law of refraction (bending of a wave as it travels from one medium to the other), while translucent objects do not come under the law of refraction. Examples of transparent objects are water, air, and so on. Examples of translucent objects are polythene sheets, fog, flames of the burner.

## Experiment to Determine if an Object is Translucent, Transparent, or Opaque

We can perform a simple experiment to check if an object is translucent, transparent, or opaque by nature.

• Collect the objects to be checked.
• Place a picture on a table.
• Hold an object between your eyes and the picture.
• Check if you can see the picture.
• If you can see the picture, such as the colours of the picture then the object is transparent. If you can see only the main shapes of the picture and not the details, then the object is translucent. If you cannot see the picture, then the object is opaque.

## Conclusion

It is easy to get confused with the terms translucent, transparent, and opaque. However, once you are familiar with the meaning of each term, then you will observe how different all these objects are.